Model Assumptions

Under the initial crustal stress condition, the grout of the first sequence grouting spreads horizontally from the grout outlet to the surroundings. The grout vein splitting diffusion model is shown in Fig. 2a), which shows the longitudinal profile of the round cake grout vein. The grout vein thickness is b, and the horizontal plane passing through the grouting hole is taken as the symmetrical plane. With the increase of the grout vein diffusion half diameter, the grout vein thickness gradually decreases. At the farthest diffusion distance of r_max1, the grout vein thickness decreases to 0. However, in the process of pre grouting, the grout vein compresses the upper and lower soil mass, which makes the vertical crustal stress gradually increase. For different required grout diffusion radii, different grouting pressures need to be set, so there is a r_max0 that can increase the vertical crustal stress near the grouting hole, that is, the small principal stress of rock and soil mass to be equal to the large principal stress. When the preset r_max is greater than r_max0, the direction of the large and small principal stresses changes, as shown in Fig. 2b).

In order to study the dynamic development process of the prophase and anaphase cleavage plasma veins, the following assumptions are made:

(1) Before the first grouting, the initial state of the rock and soil medium is: the direction of the large principal stress σ₁ is horizontal, and the direction of the small principal stress σ₃ is vertical. After the first sequence of grouting, the horizontal grout vein only compresses the upper and lower rock and soil mass, and the horizontal principal stress changes little, so it is assumed that the horizontal principal stress is still σ₁. The vertical principal stress becomes σ₃’, and the changed vertical principal stress is greater than the horizontal principal stress, namely σ₃’ becomes the major principal stress;

(2) Under the condition of controllable pressure, the pressure rises rapidly to the splitting pressure, regardless of the influence of the initial grout bubble on the splitting process, the grout diffuses radially and symmetrically from the grouting hole to the periphery, and the width of the splitting path of the first grouting grout diffuses horizontally. After the first sequence grouting is completed, the secondary grouting will be carried out after the ground stress recovers and becomes stable. Due to the change in the direction of major and minor principal stresses, during the subsequent splitting process, the grout vein will spread in a round cake shape along the vertical direction from the grouting hole, and the width of the splitting path will decrease along the diffusion direction, which is the largest at the grouting hole and the smallest at the splitting tip;

(3) The slurry is homogeneous, isotropic, and incompressible Newtonian fluid, and its flow and diffusion mode is laminar flow. During the flow process, the influence of the gravity factor of the slurry itself on the slurry diffusion process is ignored. The speed on the center line of the circular cake interface is the largest, the closer to the rock and soil wall, the smaller the speed is, and the speed on the wall is zero;

Fig. 2.

Propagation model of fracture grouting: Schemes follow another format. If there are multiple panels, they should be listed as: a) Splitting diffusion model of grout vein for preceding grouting; b) Splitting diffusion model of grout vein for subsequent grouting.

(4) The condition for stopping the expansion of the grout pulse is that the grouting is stopped or the grout pressure at the tip of the round cake of the grout pulse decreases below the splitting pressure. Respectively, during the first sequence grouting, the slurry pressure at the tip of the round cake splitting slurry vein decreases to a small principal stress σ₃. During subsequent grouting, the slurry pressure at the tip of round cake splitting grout vein decreases to a small principal stress σ₁.

(5) The pressure p of the first grouting slurry compresses the surrounding soil mass, causing the rock and soil mass within the range D to compress and deform ε-p If the p relation conforms to formula (2), the thickness expression of the pulp vein is:

The subsequent grout pressure p₂ compresses the surrounding soil, which makes the rock and soil mass in the range D undergoes compression deformation. However, since the horizontal grouting pulse of the first sequence grouting only affects the stress of the rock mass in the range D, and the extension length of the vertical split grouting pulse is much longer than that of D, the influence of the first sequence grouting on the ε-p relationship of the rock mass on both sides of the second sequence grouting pulse is not considered, that is, the values of A and B are unchanged.

(6) The loss of secondary pulpy veins and other grout caused by uneven filling and unequal grout is not considered;

(7) Constant grouting pressure can be achieved by adjusting the grout flow rate.

Determination of Splitting Pressure

When the grout cannot penetrate into the geotechnical pores, it will accumulate into slurry bubbles at the grouting outlet, and when the pressure increases to a certain extent, the grout will split the geotechnical mass to form slurry veins and spread around. The grouting pressure for splitting is called split pressure or split pressure, and the occurrence and development mechanism of split grouting is obtained based on the expansion and research of the hydraulic splitting principle. When the grouting pressure is greater than the sum of the minimum principal stress in the reinforcement zone and the tensile strength of rock and soil mass, split grouting will occur.

The damage form of grout splitting to rock and soil mass is tensile failure. If there are original cracks or weak surfaces at the grouting outlet, grout will preferential split the weak area. If there is no weak zone, the research method of hydraulic splitting is used for reference, as shown in Fig. 3. The rock and soil mass are assumed as uniform medium and isotropy, the vertical direction around the grouting outlet is the minimum principal stress σ₃ the horizontal stress is the maximum principal stress σ₃, the grouting pressure is p, the radius of the grouting hole is r₀, and the tensile stress is negative and the compressive stress is positive. The included angle between the pulp bubble and the X axis of the coordinate system is θ, the stress state of any point A whose distance from the center of the pulp bubble r is:

(4)

σr=σ1+σ32(1−r02r2)+r02r2p+σ1−σ32(1−r02r2)(1−3r02r2)cos2θσθ=σ1+σ32(1+r02r2)−r02r2p−σ1−σ32(1+3r02r2)cos2θτrθ=−σ1−σ32(1−r02r2)(1+3r02r2)sin2θ}

Fig. 3.

Stress distribution near the grouting orifice.

Where σ_r is radial stress, σ_θ is tangential stress and τ_rθ is shear stress. As the radius r increases, the slurry pressure gradually decreases, and the stress state at r = r₀ is:

(5)

σr=pσθ=σ1+σ3−p−2cos2θ(σ1−σ3)τrθ=0}

According to Equation (5), when the grouting pressure is large enough, it is negative, and when θ = kπ, (k = 0, 1, 2.) When cos2θ = 1, the absolute value of tensile stress |σ_θ| is the maximum, and the stress state at this position is:

Fig. 4.

Stress state when soils breaking near the grouting orifice.

(6)

σrpσθ=3σ3−σ1−pτrθ=0}

When θ = kπ, the tensile stress reaches its maximum value in the horizontal direction 3σ₃-σ₁-p, as shown in Fig. 4. If the absolute value of the horizontal tensile stress |σ_θ| is greater than the maximum tensile strength of the medium in the region σ_m, the rock and soil mass will be split in the horizontal direction, that is, splitting slurry veins will occur when the grouting pressure p increases to 3σ₃-σ₁-σ_m.

According to the Mohr-Coulomb criterion:

(7)

τ=c+σtanφ

Where, τ is the shear stress, c is the cohesive force of rock and soil materials, σ is the normal stress acting on the plane, φ is the Angle of internal friction of rock and soil materials. Fig. 4 shows the position of stress Mohr circle at the grouting outlet when the rock and soil mass are about to be destroyed, which is tangent to the tensile strength line. Radial stress σ_r and tangential stress σ_θ is the maximum and minimum principal stresses respectively. Any point on Mohr’s circle is an inclined plane α parallel to the minimum principal stress. The horizontal coordinate is the normal stress on the inclined plane, and the vertical coordinate is the shear stress on the inclined plane.

The center of a Mohr’s circle is (σr+σθ2,0) and the radius is σr−σθ2. The following stress relationship exists at the tangent point:

(8)

σ=σr+σθ2+σr−σθ2cos2ατ=σr−σθ2sin2αsin2α=cosφcos2α=−sinφ}

Combined with (6), (7) and (8), we can get:

(9)

p=(1+sinφ)3σ3−σ12+cosφ·c

The grouting pressure obtained by Equation (9) is the splitting pressure of the rock and the soil medium, which is related to the cohesion of the rock and soil mass, the Angle of internal friction and the major principal stress, and the direction is parallel to the major principal stress direction.

First Sequence Horizontal Splitting Diffusion

Slurry Splitting Model

The splitting process of grout in rock and soil mass needs to consider the compression characteristics of rock and soil mass, as well as the rheological properties of grout. The dynamic diffusion process of grout is analyzed below.

If the grout is a Newtonian fluid, the force analysis is shown in Fig. 5, and the shear stress expression is:

(11)

τ=μγ

As shown in Fig. 5, it is assumed that the movement of grout in the crack is equivalent to the flow in a section, which starts from the grouting outlet and diverges to all sides. There is an axisymmetric grout fluid column in the section of the grout vein, and the thickness of the grout fluid column at the diffusion radius of r is b₁. A grout fluid column at any axis with the length of dr and the radius of a less than b₁/2 is taken, and the mass of the fluid colup₁ is the pressure exerted by the grout, τ is the shear stress exerted by the grout fluid column, the grout density is ρ, and its force equation is:

(12)

2adp1+2τdr1=0

Fig. 5.

Propagation model of fracture grouting.

After transformation, we can get:

(13)

τ=−adp1dr1

The above formula shows that the shear stress τ. The value of is proportional to the distance from the central axis, so the shear stress near the centerline of the pipe τ is very small. Should be equal to zero here. Therefore, for Bingham fluid in this section, there is a cylinder with radius a₀, and the shear stress of fluid in the cylinder τ shear stress less than radius a₀ of the cylinder τ₀, that is, the fluid is relatively static within radius a₀ and the overall velocity is the same as v₀, while at a₀ ≤ a ≤ b₁/2, the fluid velocity is different, and it can be obtained that:

(14)

a0=−τ0dr1dp1

According to the force balance formula:

(15)

dvda=aμdp1dr1

By integrating equation (15), we can get:

(16)

v=dp1dr1a22μ+c

In the formula, c is the integral constant. Since the velocity v at a = b₁/2 is 0, it can be obtained that the integral constant c is:

(17)

c=−dp1dr1b128μ

So, the expression of velocity v is:

(18)

v=dp1dr14a2−b128μ

As with Bingham fluids, the average velocity can be obtained from the total flows of the pulp:

(19)

v―=qb1=2∫0b12vdab1=−dp1dr1b1212μ

After sorting out formula (19), we get:

(20)

dp1dr1=−12μv―b12

During the diffusion process of round cake slurry vein, the grout flow through the section at any radius r₁ is equal to the grouting flow, and the grouting flow Q₁ has the following relationship with the slurry speed v̅ :

(21)

Q1=2πr1b1v―

By combining (20) and (21), it can be obtained that the pressure gradient of Newtonian fluid slurry pulse is:

(22)

dp1dr1=−6μQ1πr1b13

By combining (22) and (3) can obtain:

(23)

A3D3(p1+B−σ3+B)3dp1=−6μQ1πr1dr1

After integrating the above equation, we can get:

(24)

A3D3[25(p1+B)52−32σ3+B(p1+B)2−(σ3+B)32p1+2(σ3+B)(p1+B)32]=−6μQ1πlnr1+c1

Where c₁ is the integral constant, when r = r_max1, p₁ = σ₃. Substituting the boundary conditions into the above equation, we can get:

(25)

c1=A3D3[910(σ3+B)52−σ3(σ3+B)32]+6μQ1πlnrmax1

The relation between the diffusion radius of Newtonian fluid slurry pulse and the slurry pressure can be obtained by taking (25) into (24):

(26)

r1=rmax1eπA3D36μQ1[910(σ3+B)52−σ3(σ3+B)32−25(p1+B)52+32σ3+B(p1+B)2+(σ3+B)32p1−2(σ3+B)(p1+B)32]

According to the relationship between the diffusion radius and the grout pressure in the above formula, the grout pressure at different diffusion radii can also be obtained. When r₁ = r₀ (r₀ is the radius of the grouting pipe) is known, the grout pressure is equal to the pressure at the grouting pipe orifice, so the relationship between the maximum diffusion radius r_max1 and the grouting pipe orifice pressure p₀₁ can be obtained:

(27)

rmax1=r0πA3D36μQ1[910(σ3+B)52−σ3(σ3+B)32−25(p01+B)52+32σ3+B(p01+B)2+(σ3+B)32p01−2(σ3+B)(p01+B)32]

Considering the loss hf along the grouting pressure, the relationship between the pump outlet pressure and the grouting pipe orifice pressure is as follows:

(28)

pset=hfρg+p01

Where, p_set is the output pressure of grouting pump, Pa; h_f is the loss along the way, m; ρ is the medium density, kg/m³. In conclusion, the formula of grouting pump outlet pressure of Newtonian fluid grout can be obtained according to the set grout diffusion radius:

(29)

−25(pset+B−hfρg)52+32σ3+B(pset+B−hfρg)2+(σ3+B)32pset−2(σ3+B)(pset+B−hfρg)32+910(σ3+B)52−σ3(σ3+B)32−6μQ1πA3D3ln(r0rmax1)=0

Put the above equation into polynomial of degree 5:

(30)

−25x5+A1x4+C1x3+D1x2+E1=0B1=B−hfρg,B=Es02ε224(p′−Es0ε2)2x=p01+B1A1=32σ3+BC1=−2(σ3+B)D1=(σ3+B)32E1=910(σ3+B)52−(B−hfρg+σ3)(σ3+B)32−6μQ1πε23D3ln(r0rmax1)}

For a given r_max1, it is unrealistic to require the 5^th degree polynomial of solution (30). In this paper, the corresponding relationship between grouting pressure and diffusion radius is obtained through reverse fitting. With the increase of grouting pressure, the diffusion radius of grout, r_max1, gradually increases. The two are positively correlated and one-to-one corresponding. Therefore, in order to obtain the grouting pressure corresponding to different diffusion radius r_max1, first find the slurry diffusion radius under different grouting pressure according to Formula (27).

The initial value of grouting pressure is set as p_h0, and the corresponding slurry diffusion radius is r_h0. The initial value p_h0 is assigned as the splitting pressure (1+sinφ)3σ3−σ12+cosφ·c. Considering the convenience of solving the fitting relation and the experimental error, it is determined that a diffusion radius is calculated every 10 kPa:

(31)

phi=ph0+10i,(i=1,2,3…n)rhi=r0eπA3D36μQ1[910(σ3+B)52−σ3(σ3+B)32−25(phi+B)52+32σ3+B(phi+B)2+(σ3+B)32phi−2(σ3+B)(phi+B)32]}

Since the amplitude and measurement error of the output pressure of the grouting pump are far greater than 10 kPa, the approximate value of the grouting pressure setting value can be obtained as follows:

(32)

p01=phi+phi+1−phirhi+1−rhi(rmax1−rhi),(rhi<rmax1≤rhi+1)

Calculation Method of Grouting Time

In the actual construction process, the split grout vein usually extends from several meters to more than ten meters, and the grout vein thickness is only a few millimeters. The change rate of the thickness in the slender grout vein is not large. Therefore, in the process of calculating the grouting time, the grout vein thickness b₁ is approximately linear, and the grout vein section can be assumed to be triangular, as shown in Fig. 6.

According to the interface of the pulp pulse, the volume of slurry consumed by the round cake pulp pulse is:

(33)

V11=2·13πrmax12b01=2πrmax12b013

Where, V₁₁ is the volume of round cake grout vein, and b₀₁ is the thickness of grout vein at the grouting hole. Wherein, b01=AD(p01+B−σ3+B), the volume of round cake pulp is:

(34)

V11=2πrmax12AD(p01+B−σ3+B)3

Fig. 6.

Propagation model of fracture grouting.

According to the Q₁ change curve, the total volume of grout discharged by the grouting pump is:

(35)

V01=∫0t1Q1dt

The total volume of grout discharged by the grouting pump is equal to the amount of grout retained in the grouting pipeline V₂ plus the volume of round cake grout vein V₁₁, so the grouting time t₁ under the grouting pressure p₀₁ when the set diffusion radius is r_max1 can be obtained according to the following formula.

(36)

∫0t1Q1dt=2πrmax12AD(p01+B−σ3+B)3

Testing Device and Materials

The split grouting model test system includes six parts: model frame unit, ground stress loading unit, ground stress monitoring unit, grouting unit, grouting pump monitoring unit, grouting pump control unit, etc. The model frame unit includes: model frame, grouting pipe, ground stress loading unit includes: hydraulic station, hydraulic cylinder, hydraulic tandem device, high-pressure hose, and ground stress monitoring unit includes: earth pressure cells, XL2101G static strain gauge, and computer. Grouting unit includes: SDU-0.5S-23 Wankel pump, slurry storage bucket, hand-held mixer, high-pressure pipeline. Grouting pump monitoring unit: flow sensor, pressure sensor, torque sensor. Grouting pump control unit: stepping motor, PLC control cabinet, AC motor, system layout is shown in Fig. 7.

The soil used in this test is from a soil field in Weifang. According to the results of consolidation test and shear test, the initial compression modulus E_s0 of soil mass and the strain at the stress value of 2000kPa can be obtained ε₂. Cohesion c, internal friction angle φ. The specific characteristics are shown in Table 1.

According to the data in Table 1 and Formula (2) and (3), the compression characteristic coefficients A.B and C of soil for test can be obtained as follows:

42.5R ordinary Portland cement is selected for the test. The water-cement ratio of cement slurry is 1:1. Ignoring the change of slurry viscosity with time, an SV-100 vibrating wire viscometer is used to detect the shift in cement slurry viscosity with time. A laser particle size analyzer is used to measure the particle size distribution of cement samples. The slurry viscosity and particle size distribution are shown in Fig. 8. The average viscosity of grout and the characteristic diameter of grouting material is taken as d90. The statistical results are shown in Table 2.

Fig. 7.

Model test system: 1. Computer; 2. Hydraulic station; 3. Strain gauge; 4. Model frame; 5. PLC control cabinet; 6. AC motor; 7. Stepping motor; 8. Stepless transmission; 9. Torque sensor; 10. SDU-0.5-23; 11. Pressure sensor; 12. Slurry storage tank; 13. Electromagnetic flowmeter.

Fig 8.

Feature of the grout: a) Viscosity change over time; b) Particle size distribution of cement.

Test Procedure

Filling Soil and Place Earth Pressure Cells

The injected soil mass model is made of a cube with a length, width and height of 100 cm. The grouting pipe is inserted vertically from the top, and the grouting outlet is located at the center of the cube. The horizontal split round cake pulse of the prior grouting occurs on the 50cm horizontal plane, as shown in Fig. 9. The vertical split round cake pulse generated during the secondary grouting is perpendicular to the horizontal round cake pulse, but the direction of the vertical round cake surface is uncertain. In this experiment, the horizontal stress is applied in two mutually perpendicular directions. Therefore, the direction of the vertical pulse is limited to the two potential directions of the front and right view. The vertical split round cake pulse generated during the secondary grouting is perpendicular to the horizontal round cake pulse, but the direction of the vertical round cake surface is uncertain. In this experiment, the horizontal stress is applied in two mutually perpendicular directions. Therefore, the direction of the vertical pulse is limited to the two potential directions of the front and right side view.

In Fig. 9, the soil mass in the model is divided into 10 layers, each of which is 10 cm. The horizontal splitting of the preceding grouting occurs in the 50 cm soil layer. In order to avoid the interference of the embedded earth pressure cells on the direction of the two circular cake veins, the arrangement of the earth pressure cells is dispersed in the space between the two possible directions of the horizontal and vertical cake veins, as follows:

A total of 15 earth pressure cells are arranged in the model, and 9 are arranged in the 60cm soil layer, namely s61, s62, s63, s64, s65, s66, s67, s68 and s69. Among them, s61, s62, s63, s64, s65 and s66 are placed vertically to monitor the horizontal ground stress. s61, s62, s63 face the right view direction, s64, s65, s66 face the face direction; Three layers, s71, s72 and s73, were arranged in the 70cm soil layer. s71 and s72 were placed vertically to monitor the horizontal ground stress, with s71 facing the right view direction and s72 facing the face direction. Also, three units, s81, s82 and s83, were placed vertically in the 80 cm soil layer to monitor the horizontal ground stress, with s81 facing the right view direction and s82 facing the face direction. Fill the injected soil medium layer by layer, and before the soil layer exceeds the height of the lead hole, all the soil pressure gauges are introduced into the model through the lead hole. The sensor data line is derived along the outer ring according to the principle of separating the pulping pulse path, and a reasonable length of the data line is reserved before burying the lead hole.

Fig. 9.

Three-dimensional layout of earth pressure cells.

Apply Crustal Stress

The major and minor principal stresses of the split grouting model test are set as 200kPa and 100kPa respectively, and the horizontal control system and vertical control system of the hydraulic station are loaded respectively until the horizontal stress and vertical stress reach the set value. Record the stress values of earth pressure cells at s63, s71, and s81 to display the horizontal stress, and record the stress values of earth pressure cells at s69, s68, and s67 to display the vertical stress. The stress change curve is shown in Fig. 10.

Grouting Process

The grouting process is divided into two injections. Under the action of large horizontal principal stress, the first sequence grouting will cause the spread of horizontal fracturing fluid. According to the cohesion c = 27.5 kPa and internal friction angle φ = 22.83° in Table 1, large principal stress σ₁ = 200kPa and small principal stress σ₃ = 100kPa, it can be obtained that the splitting pressure of the pre-grouting is:

For the convenience of rounding, p_h0 selects the approximate value of the splitting pressure of 100 kPa, and the influence range D is 30 cm. Due to the change of grouting flow at any time, the diffusion radius and grouting time of corresponding grouting pressure cannot be accurately obtained. According to the output performance curve of SDU-0.5S-23, the grouting flow is selected as a constant value of 5 L/min. Setting the maximum radius of slurry horizontal diffusion round cake slurry vein as 0.4 m, it can be obtained that the set value of grouting pressure is 391.59 kPa, and the estimated grouting time is 71.1 s.

Fig. 10.

Filling soil and place ground stress sensors: a) Vertical stress loading curve; b) Horizontal stress loading curve.

Since the accurate secondary grouting splitting pressure cannot be calculated in advance, the secondary splitting pressure should be greater than that of the previous grouting. The p_v0 should be 150kPa, and the grouting flow should also be 6 L/min. Setting the maximum radius of slurry horizontal diffusion round cake slurry vein as 0.4 m, it can be obtained that the set value of grouting pressure is 473.2 kPa, and the estimated grouting time is 55.3 s. See Table 3 for statistics of control parameters of two injections.

Test Result

Change Monitoring of Ground Stress

The initial grouting process lasted 72 s in total. The fluctuation of the ground stress during this period is shown in Fig. 11. The values monitored by the earth pressure cells s61, s62, s63, s71, and s81 that monitor the horizontal stress fluctuated around the initial ground stress of 200 kPa, and then increased slightly, indicating that the horizontal splitting grout pulse has little influence on the horizontal stress; The values monitored by the vertical earth pressure cells s67, s68, s69, s73 and s83 are gradually increased under the compression of the horizontal split grout vein. With the increase of the horizontal distance and vertical distance from the grouting hole, the response speed of the vertical crustal stress is faster, and the increase of the vertical crustal stress is larger. Finally, the vertical crustal stress monitored by s67, s68, s69, s73, and s83 are 218.45 kPa, 226.63 kPa, 241.9 kPa, 195.56 kPa, and 155.71 kPa, respectively, it can be found that the vertical crustal stress near the grouting hole has been greater than the horizontal crustal stress, and the direction of the large and small crustal stress near the grouting hole has changed, providing conditions for the vertical splitting of the secondary grouting grout.

Fig. 11.

Stress fluctuation of the first grouting: a) Horizontal stress by first grouting; b) Vertical stress by first grouting.

Fig. 12.

Stress fluctuation of the second grouting: a) Horizontal stress by second grouting; b) Vertical stress by second grouting.

Fig. 13.

Removing the soil and expose the grout veins.

After the completion of the first sequence grouting, the model frame shall stand for 2 h, and the cement slurry shall be reconfigured for secondary grouting. The duration of secondary grouting is 55 s. As shown in Fig. 12, the data monitored by the earth pressure cells s61, s62, s63, s71, and s81 that monitor the horizontal stress starts to rise at about 200 kPa. The greater the horizontal distance and vertical distance from the grouting hole, the faster the response speed of horizontal ground stress and the greater the added vertical stress. The final vertical ground stress monitored by s61, s62, s63, s71, and s81 are 235.73 kPa, 249.52 kPa, 293.12 kPa, 269.21 kPa 259.44 kPa； The values monitored by the vertical earth pressure cells s67, s68, s69, s73 and s83 fluctuate around the initial value, and are not significantly affected by the vertical splitting grout pulse.

The earth pressure cells s64, s65, s66, s72, and s82 that monitor the horizontal stress in the front view direction are not subject to compression, and the monitored data are not significantly affected by the initial ground stress horizontal and vertical split grout veins.

Expose the Split Plasma Vein

After grouting, gradually remove the grouting equipment, and facilities around the model frame, dismantle the model frame in layers, excavate and expose the split grout vein as shown in Fig. 13. The horizontal split grout vein and the vertical split grout vein can be seen. Because of the uneven soil filling in the test process, the vertical grout vein did not spread completely in the vertical direction, the diffusion diameter of the horizontal grout vein was about 83.79 mm, and the vertical grout vein was about 75.92 mm.