Discrimination Method for Local Stability of Water-rich Soft Soil Stratum

Abstract

The present invention relates to a method for judging the local stability of a water-rich soft soil stratum, which includes the following steps: determining the soil layer parameters at the position to be constructed, and determining the construction parameters of the diaphragm wall to be constructed; calculating the moment M based on the soil layer parameters and the construction parameters s , moment M a , moment M w , shear force moment M t , anti-shear force moment M f and self-weight acting moment M g ; calculating the total moment M0 received by the local sliding body according to the moment M a , moment M w , shear force moment M t , anti-shear force moment M f and self-weight acting moment M g ; comparing the total moment M0 with the moment M s , if the moment M s is greater than or equal to the total moment M0, the slurry pressure of the diaphragm wall to be constructed can support the local sliding body. The present invention effectively solves the problem that the local instability of the soft interlayer in the water-rich stratum is not easily detected. By calculating the moment values of each layer of the stratum, it is judged whether the slurry pressure of the diaphragm wall is sufficient to support the local sliding body in the soft interlayer, which has guiding significance for the construction of the diaphragm wall.

Description

Technical Field

[0001] The present invention relates to the field of construction, and particularly refers to a method for judging the local stability of a water-rich soft soil stratum. Background Art

[0002] With the continuous advancement of the urbanization process, the available above-ground space in cities is becoming less and less, and more and more vehicles have brought huge pressure to urban traffic. To solve this development problem, people have begun to turn their attention to the underground space with great potential. The development of urban rail transit has greatly alleviated the pressure on urban above-ground traffic. With the accelerating development of the underground space in big cities, underground projects are gradually going from shallow to deep, and there are more and more deep foundation pit projects.

[0003] For deep foundation pit projects, diaphragm walls are the most suitable type of retaining structure. However, in coastal cities, the stratum type is mainly water-rich soft soil stratum and will have soft interlayers. When the excavation depth is too large, local instability of the soft interlayers is likely to occur. When excavating diaphragm walls in deep soft soil strata, due to the complexity of the strata, local instability of the soft interlayers is more likely to occur, posing a greater potential safety hazard. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art, provide a method for judging the local stability of a water-rich soft soil stratum, solve the problem that local instability of the soft interlayers in the water-rich stratum is not easily detected, judge whether the mud pressure of the diaphragm wall is sufficient to support the local sliding body in the soft interlayer by calculating the moment magnitudes of various factors of the stratum, which has guiding significance for the construction of the diaphragm wall and ensures the construction quality and safety.

[0005] The technical solution to achieve the above purpose is as follows:

[0006] The present invention provides a method for judging the local stability of a water-rich soft soil stratum, including the following steps:

[0007] Determine the soil layer parameters at the construction position to be constructed according to the geological exploration report, and determine the construction parameters of the diaphragm wall to be constructed;

[0008] Calculate the moment M of the mud pressure of the diaphragm wall on the local sliding body in the soft interlayer, s the moment M of the soil pressure of the soil above the soft interlayer on the local sliding body, a the moment M of the groundwater pressure on the local sliding body, w the moment M of the shear force of the soil around the local sliding body on the local sliding body, t the moment M of the anti-shear force of the soil around the local sliding body on the local sliding body, f and the moment M of the self-weight acting force of the local sliding body g ;

[0009] According to the moment M a and the moment M w and the shear force moment M t and the anti-shear force moment M f and the self-weight acting moment M g calculate the total moment M0 received by the local sliding body;

[0010] Compare the total moment M0 with the moment M s , if the moment M s is greater than or equal to the total moment M0, the mud pressure of the diaphragm wall to be constructed can support the local sliding body.

[0011] The present invention proposes a method for judging the local stability of a water-rich soft soil stratum. By calculating the moments M s and the moment M a and the moment M w and the shear force moment M t and the anti-shear force moment M f and the self-weight acting moment M g according to the soil layer parameters and construction parameters, and then calculating the total moment M0 according to the moment M a and the moment M w and the shear force moment M t and the anti-shear force moment M f and the self-weight acting moment M g compare the total moment M0 with the moment M s . If the moment M s is greater than or equal to the total moment M0, the mud pressure of the diaphragm wall to be constructed can support the local sliding body. If the moment M s is less than the total moment M0, it cannot support the local sliding body and the mud pressure needs to be increased, that is, the specific gravity of the mud is increased, solving the problem that the local instability of the weak interlayer in the water-rich stratum is not easy to detect. By calculating the moment magnitudes of various factors of the stratum, it is judged whether the mud pressure of the diaphragm wall is sufficient to support the local sliding body in the weak interlayer, which has guiding significance for the construction of the diaphragm wall and ensures the construction quality and construction safety.

[0012] A further improvement of the method for judging the local stability of the water-rich soft soil stratum of the present invention is that when calculating the moment M s , it further includes:

[0013]

[0014] wherein, M s is the moment of the mud pressure on the local sliding body, a is the thickness of the weak interlayer, H is the thickness of the soil layer above the weak interlayer, H s is the liquid level elevation of the mud used for pouring the diaphragm wall, γs is the unit weight of the slurry used for pouring diaphragm walls in the ground.

[0015] A further improvement of the method for judging local stability of water-rich soft soil strata in the present invention lies in that when calculating the moment M a it further includes:

[0016]

[0017] where M a is the moment of the soil pressure above the soft interlayer on the local sliding body, a is the thickness of the soft interlayer, L is the width of the diaphragm wall to be formed, γ′ is the average effective unit weight of the soil layer above the soft interlayer, c is the cohesion of the soil layer above the soft interlayer, q is the surface additional load, is the internal friction angle of the soil layer above the soft interlayer, e is the irrational number, and H is the thickness of the soil layer above the soft interlayer.

[0018] A further improvement of the method for judging local stability of water-rich soft soil strata in the present invention lies in that when calculating the moment M w it further includes:

[0019]

[0020] where M w is the moment of the groundwater pressure on the local sliding body, a is the thickness of the soft interlayer, h F is the elevation of the confined water head, H is the thickness of the soil layer above the soft interlayer, H s is the elevation of the slurry surface used for pouring diaphragm walls in the ground, γ w is the unit weight of the confined water.

[0021] A further improvement of the method for judging local stability of water-rich soft soil strata in the present invention lies in that when calculating the shear force moment M t it further includes:

[0022]

[0023]

[0024]

[0025] where M t is the shear force moment of the soil around the local sliding body on the local sliding body, a is the thickness of the soft interlayer, K a is the active earth pressure coefficient, δ1 is the earth pressure on the local sliding body in the vertical direction, c0 is the cohesion of the soft interlayer soil, L is the width of the diaphragm wall to be formed, γ′ is the average effective unit weight of the soil layer above the soft interlayer, c is the cohesion of the soil layer above the soft interlayer, q is the surface additional load, is the internal friction angle of the soil layer above the weak interlayer, e is the irrational number, H is the thickness of the soil layer above the weak interlayer, is the internal friction angle of the soil mass of the weak interlayer.

[0026] A further improvement of the method for judging the local stability of the water-rich soft soil stratum of the present invention lies in calculating the anti-shearing force moment M f When calculating, it also includes:

[0027]

[0028] wherein, M f is the anti-shearing force moment of the soil around the local sliding body on the local sliding body, a is the thickness of the weak interlayer, K a is the active earth pressure coefficient, δ1 is the earth pressure on the local sliding body in the vertical direction, c0 is the cohesion of the soil mass of the weak interlayer, is the internal friction angle of the soil mass of the weak interlayer, and π is taken as 3.14.

[0029] A further improvement of the method for judging the local stability of the water-rich soft soil stratum of the present invention lies in calculating the self-weight acting moment M g When calculating, it also includes:

[0030]

[0031] wherein, M g is the self-weight acting moment of the local sliding body, a is the thickness of the weak interlayer, and γ0′ is the effective unit weight of the soil mass of the weak interlayer.

[0032] A further improvement of the method for judging the local stability of the water-rich soft soil stratum of the present invention lies in calculating the total moment M0, and it also includes:

[0033] M0 = M a + M w + M t - M f + M g

[0034] wherein, M0 is the total moment received by the local sliding body, M a is the moment of the soil pressure above the weak interlayer on the local sliding body, M w is the moment of the groundwater pressure on the local sliding body, M t is the shearing force moment of the soil around the local sliding body on the local sliding body, M f is the anti-shearing force moment of the soil around the local sliding body on the local sliding body, M g is the self-weight acting moment of the local sliding body.

[0035] A further improvement of the method for judging the local stability of a water-rich soft soil stratum in the present invention lies in comparing the total moment M0 with the moment M s , if the moment M s is less than the total moment M0, then increase the specific gravity of the slurry used for pouring the diaphragm wall.

[0036] A further improvement of the method for judging the local stability of a water-rich soft soil stratum in the present invention is that when increasing the specific gravity of the slurry used for pouring the diaphragm wall, it further includes:

[0037] Calculate the minimum slurry specific gravity and adjust the specific gravity of the slurry used for pouring the diaphragm wall according to the minimum slurry specific gravity . The calculation formula is as follows:

[0038]

[0039] wherein, is the minimum slurry specific gravity, a is the thickness of the soft interlayer, H is the thickness of the soil layer above the soft interlayer, H s is the liquid level elevation of the slurry used for pouring the diaphragm wall, and M0 is the total moment received by the local sliding body. Description of the Drawings

[0040] Figure 1 is a flow chart of the method for judging the local stability of a water-rich soft soil stratum in the present invention. Detailed Embodiments

[0041] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0042] The present invention provides a method for judging the local stability of a water-rich soft soil stratum. By calculating the moments M s , moment M a , moment M w , shear force moment M t , anti-shear force moment M f and self-weight acting moment M g based on soil layer parameters and construction parameters, and then calculating the total moment M0 according to the moments M a , moment M w , shear force moment M t , anti-shear force moment M f and self-weight acting moment M g . Compare the total moment M0 with the moment M s . If the moment M s is greater than or equal to the total moment M0, then the slurry pressure of the diaphragm wall to be constructed can support the local sliding body. If the moment M sIf it is less than the total moment M0, the local sliding body cannot be supported, and it is necessary to increase the mud pressure, that is, increase the specific gravity of the mud, which solves the problem that the local instability of the soft interlayer in the water-rich stratum is not easily detected. By calculating the moment magnitudes of various factors of the stratum, it is judged whether the mud pressure of the diaphragm wall is sufficient to support the local sliding body in the soft interlayer, which has guiding significance for the construction of the diaphragm wall and ensures the construction quality and construction safety. The method for judging the local stability of the water-rich soft soil stratum of the present invention will be described below with reference to the accompanying drawings.

[0043] Refer to Figure 1 which is a flowchart of the method for judging the local stability of the water-rich soft soil stratum of the present invention. The method for judging the local stability of the water-rich soft soil stratum of the present invention will be described below with reference to Figure 1 ,

[0044] As Figure 1 shown, the present invention provides a method for judging the local stability of a water-rich soft soil stratum, including the following steps:

[0045] Determine the soil layer parameters at the construction position to be constructed according to the geological exploration report, and determine the construction parameters of the diaphragm wall to be constructed;

[0046] Calculate the moment M of the mud pressure of the diaphragm wall on the local sliding body in the soft interlayer, the moment M of the soil pressure above the soft interlayer on the local sliding body, the moment M of the groundwater pressure on the local sliding body, the moment M of the shear force of the soil around the local sliding body on the local sliding body, the moment M of the anti-shear force of the soil around the local sliding body on the local sliding body, and the moment M of the self-weight acting force of the local sliding body according to the soil layer parameters and construction parameters; s a w t f g ;

[0047] Calculate the total moment M0 received by the local sliding body according to the moment M, the moment M, the shear force moment M, the anti-shear force moment M, and the self-weight acting force moment M; a w t f g

[0048] Compare the total moment M0 with the moment M. If the moment M is greater than or equal to the total moment M0, the mud pressure of the diaphragm wall to be constructed can support the local sliding body. s s

[0049] As a preferred embodiment of the present invention, when calculating the moment M, it further includes: s

[0050]

[0051] Among them, M s is the moment of the mud pressure on the local sliding body, a is the thickness of the weak interlayer, H is the thickness of the soil layer above the weak interlayer, H s is the liquid level elevation of the mud used for pouring the diaphragm wall, γ s is the unit weight of the mud used for pouring the diaphragm wall.

[0052] Furthermore, when calculating the moment M a , it also includes:

[0053]

[0054] Among them, M a is the moment of the soil pressure above the weak interlayer on the local sliding body, a is the thickness of the weak interlayer, L is the width of the diaphragm wall to be formed, γ′ is the average effective unit weight of the soil layer above the weak interlayer, c is the cohesion of the soil layer above the weak interlayer, q is the surface additional load, is the internal friction angle of the soil layer above the weak interlayer, e is the irrational number, H is the thickness of the soil layer above the weak interlayer.

[0055] Furthermore, when calculating the moment M w , it also includes:

[0056]

[0057] Among them, M w is the moment of the groundwater pressure on the local sliding body, a is the thickness of the weak interlayer, h F is the elevation of the confined water head, H is the thickness of the soil layer above the weak interlayer, H s is the liquid level elevation of the mud used for pouring the diaphragm wall, γ w is the unit weight of the confined water.

[0058] Furthermore, when calculating the shear force moment M t , it also includes:

[0059]

[0060]

[0061]

[0062] Among them, M t is the shear force moment of the soil around the local sliding body on the local sliding body, a is the thickness of the weak interlayer, K a$K$ is the coefficient of active earth pressure, $\delta_1$ is the earth pressure on the local sliding body in the vertical direction, $c_0$ is the cohesion of the soil in the weak interlayer, $L$ is the width of the diaphragm wall to be formed, $\gamma'$ is the average effective unit weight of the soil layer above the weak interlayer, $c$ is the cohesion of the soil layer above the weak interlayer, $q$ is the surcharge load on the ground surface, $\varphi$ is the angle of internal friction of the soil layer above the weak interlayer, $e$ is the irrational number, $H$ is the thickness of the soil layer above the weak interlayer, $\varphi_0$ is the angle of internal friction of the soil in the weak interlayer.

[0063] Specifically, when calculating the anti-shearing force moment $M$ f it also includes:

[0064]

[0065] where $M$ f is the anti-shearing force moment of the soil around the local sliding body on the local sliding body, $a$ is the thickness of the weak interlayer, $K$ a is the coefficient of active earth pressure, $\delta_1$ is the earth pressure on the local sliding body in the vertical direction, $c_0$ is the cohesion of the soil in the weak interlayer, $\varphi_0$ is the angle of internal friction of the soil in the weak interlayer, and $\pi$ is taken as 3.14.

[0066] Furthermore, when calculating the self-weight action moment $M$ g it also includes:

[0067]

[0068] where $M$ g is the self-weight action moment of the local sliding body, $a$ is the thickness of the weak interlayer, and $\gamma_0'$ is the effective unit weight of the soil in the weak interlayer.

[0069] Furthermore, when calculating the total moment $M_0$, it also includes:

[0070] $M_0 = M$ a + $M$ w + $M$ t - $M$ f + $M$ g

[0071] where $M_0$ is the total moment on the local sliding body, $M$ a is the moment of the soil pressure above the weak interlayer on the local sliding body, $M$ w is the moment of the groundwater pressure on the local sliding body, $M$ t is the shearing force moment of the soil around the local sliding body on the local sliding body, $M$ f is the anti-shearing force moment of the soil around the local sliding body on the local sliding body, $M$ g is the self-weight action moment of the local sliding body.

[0072] Furthermore, compare the total moment M0 with the moment M s , if the moment M s is less than the total moment M0, then increase the specific gravity of the slurry used for pouring the diaphragm wall.

[0073] Specifically, when increasing the specific gravity of the slurry used for pouring the diaphragm wall, it further includes:

[0074] Calculate the minimum slurry specific gravity and adjust the specific gravity of the slurry used for pouring the diaphragm wall according to the minimum slurry specific gravity , and the calculation formula is as follows:

[0075]

[0076] wherein, is the minimum slurry specific gravity, a is the thickness of the soft interlayer, H is the thickness of the soil layer above the soft interlayer, H s is the liquid level elevation of the slurry used for pouring the diaphragm wall, and M0 is the total moment received by the local sliding body.

[0077] The specific implementation manner of the present invention is as follows:

[0078] There is a soft interlayer in the water-rich soft soil stratum, and there is a certain distance between the soft interlayer and the surface of the stratum. A local sliding body is formed in the soft interlayer. When excavating the trench wall and pouring cement in the water-rich soft soil stratum to form a diaphragm wall, the local sliding body may be locally unstable, which has a greater impact on the construction;

[0079] Determine the soil layer parameters according to the geological exploration report and determine the construction parameters of the diaphragm wall to be constructed;

[0080] Calculate the moment M of the slurry pressure of the diaphragm wall on the local sliding body in the soft interlayer s , the moment M of the soil pressure above the soft interlayer on the local sliding body a , the moment M of the groundwater pressure on the local sliding body w , the shear force moment M of the soil around the local sliding body on the local sliding body t , the anti-shear force moment M of the soil around the local sliding body on the local sliding body f and the self-weight moment M of the local sliding body g ;

[0081] According to the moment M a , the moment M w , the shear force moment M t , the anti-shear force moment M f and the self-weight moment M gThe total moment M0 exerted on the local sliding body is calculated;

[0082] Compare the total torque M0 with the torque M s , if the moment M s If the total moment M0 is greater than or equal to the total moment M0, the mud pressure of the underground continuous wall to be constructed can support the local sliding body. s If it is less than the total moment M0, the mud pressure of the underground continuous wall to be constructed cannot support the local sliding body, and the weight of the mud needs to be adjusted;

[0083] According to the moment M s The minimum mud weight is calculated. Determine the weight of cement used for pouring underground continuous walls. The cement weight can be slightly larger than the minimum mud weight. The value of the underground continuous wall formed by pouring can support the local sliding body and thus maintain the stability of the underground structure.

[0084] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A method for judging the local stability of a water-rich soft soil stratum, characterized in that, Including the following steps: Determine the soil layer parameters at the construction location according to the geological exploration report, and determine the construction parameters of the diaphragm wall to be constructed; Calculate the moment M of the slurry pressure of the diaphragm wall on the local sliding body in the weak interlayer based on the soil layer parameters and the construction parameters s and the moment M of the soil pressure above the weak interlayer on the local sliding body a and the moment M of the groundwater pressure on the local sliding body w and the shear force moment M of the soil around the local sliding body on the local sliding body t and the anti-shear force moment M of the soil around the local sliding body on the local sliding body f and the self-weight acting moment M of the local sliding body g ; According to the moment M a and the moment M w and the shear force moment M t and the anti-shear force moment M f and the self-weight acting moment M g calculate the total moment M0 received by the local sliding body; Compare the total moment M0 with the moment M s , if the moment M s is greater than or equal to the total moment M0, the mud pressure of the diaphragm wall to be constructed can support the local sliding mass; When calculating the total moment M0, it also includes: M0 = M a + M w + M t - M f + M g Among them, M0 is the total moment acting on the local sliding mass, M a is the moment of the soil pressure above the weak interlayer acting on the local sliding mass, M w is the moment of the groundwater pressure acting on the local sliding mass, M t is the moment of the shear force of the soil around the local sliding mass acting on the local sliding mass, M f is the moment of the anti-shear force of the soil around the local sliding mass acting on the local sliding mass, M g is the moment of the self-weight acting force of the local sliding mass; Compare the total moment M0 with the moment M s , if the moment M s is less than the total moment M0, increase the specific gravity of the slurry used for casting the diaphragm wall; when increasing the specific gravity of the slurry used for casting the diaphragm wall, it also includes: Calculate the minimum mud density And based on the minimum mud density Adjust the density of the mud used for pouring the diaphragm wall. The calculation formula is as follows: Among them, is the minimum mud specific gravity, a is the thickness of the weak interlayer, H is the thickness of the soil layer above the weak interlayer, H s is the liquid level elevation of the mud used for casting the diaphragm wall, and M0 is the total moment acting on the local sliding body.

2. The method for judging the local stability of a water-rich soft soil stratum according to claim 1, characterized in that, Calculate the torque M s When calculating, it also includes: Among them, M s is the moment of the mud pressure on the local sliding body, a is the thickness of the weak interlayer, H is the thickness of the soil layer above the weak interlayer, H s is the liquid level elevation of the mud used for casting the diaphragm wall, γ s is the unit weight of the mud used for casting the diaphragm wall.

3. The method for judging the local stability of a water-rich soft soil stratum according to claim 1, characterized in that, Calculate the torque M a When calculating, it also includes: Among them, M a is the moment of the soil pressure above the weak interlayer on the local sliding body, a is the thickness of the weak interlayer, L is the width of the diaphragm wall to be formed, γ' is the average effective unit weight of the soil layer above the weak interlayer, c is the cohesion of the soil layer above the weak interlayer, q is the additional surface load, is the internal friction angle of the soil layer above the weak interlayer, e is the irrational number, and H is the thickness of the soil layer above the weak interlayer.

4. The method for judging the local stability of a water-rich soft soil stratum according to claim 1, characterized in that, Calculate the torque M w When calculating, it also includes: Among them, M w is the moment of the groundwater pressure on the local sliding mass, a is the thickness of the weak interlayer, h F is the elevation of the confined water head, H is the thickness of the soil layer above the weak interlayer, H s is the elevation of the liquid level of the slurry used for casting the diaphragm wall, γ w is the unit weight of the confined water.

5. The method for judging the local stability of a water-rich soft soil stratum according to claim 1, characterized in that, Calculating the shear force moment M t also includes: Among them, M t is the shear force moment of the soil around the local sliding body on the local sliding body, a is the thickness of the weak interlayer, K a is the active earth pressure coefficient, δ1 is the earth pressure in the vertical direction on the local sliding body, c0 is the cohesion of the soil in the weak interlayer, L is the width of the diaphragm wall to be formed, γ' is the average effective unit weight of the soil layer above the weak interlayer, c is the cohesion of the soil layer above the weak interlayer, q is the surface additional load, is the internal friction angle of the soil layer above the weak interlayer, e is the irrational number, H is the thickness of the soil layer above the weak interlayer, is the internal friction angle of the soil in the weak interlayer.

6. The method for judging the local stability of a water-rich soft soil stratum according to claim 5, characterized in that, Calculating the anti-shearing force moment M f When calculating, it further includes: Among them, M f is the moment of the shear resistance force of the soil around the local sliding body on the local sliding body, a is the thickness of the weak interlayer, and K a is the active earth pressure coefficient, δ1 is the earth pressure in the vertical direction on the local sliding body, c0 is the cohesion of the soil in the weak interlayer, is the internal friction angle of the soil in the weak interlayer, and π is taken as 3.

14.

7. The method for judging the local stability of a water-rich soft soil stratum according to claim 1, characterized in that, Calculating the self-weight acting moment M g also includes: Among them, M g is the self-weight acting moment of the local sliding body, a is the thickness of the weak interlayer, and γ0' is the effective unit weight of the soil in the weak interlayer.

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