Method for calculating and analyzing anti-upheaval stability of river-adjacent narrow foundation pit

Abstract

The invention provides a method for calculating anti-upheaval stability of a river-adjacent narrow foundation pit, which comprises the following steps of: introducing four parameters including a slope angle and a river-adjacent distance which are related to terrain as well as acting force and seepage force which are generated on the foundation pit by river water level variation into a traditional calculation method by considering that an arc generates a blocking effect on a side soil body and a supporting structure during sliding upheaval, and calculating the anti-upheaval stability of the river-adjacent narrow foundation pit. And obtaining a calculation result of the anti-upheaval stability of the river-near type narrow foundation pit. Wherein acting force and seepage force are generated on the foundation pit by the slope angle of the soil body at the middle-upper part outside the pit, the river-adjacent distance and the river water level change. The two parameters of the slope angle of the upper soil body in the soil body outside the foundation pit and the river-adjacent distance are used for reflecting and calculating the problem that the terrain of the soil body outside the river-adjacent narrow foundation pit is uneven, and the defect that the terrain factors outside the foundation pit are not considered in a traditional method is overcome. The two parameters of acting force and seepage force generated by river water level changes on the foundation pit are used for reflecting the problem that calculation of the river-near-river type narrow foundation pit is influenced by a river outside the foundation pit, and the advantage that influence factors of the river outside the foundation pit are not considered in a traditional method is made up.

Description

Technical Field

[0001] The invention relates to the field of foundation pit engineering, and mainly to a method for calculating the anti-uplift stability of a narrow foundation pit near a river. Background Art

[0002] With the development of national construction, there are many rivers and lakes in cities, and urban construction projects are constantly updated and iterated with the progress of the times. Due to the needs of urban ecology, most of these projects will be close to urban rivers, and narrow foundation pit projects will inevitably be formed during the construction process. First, the development of urban construction has led to crowded urban space, and the excavation space of the foundation pit is limited; second, the characteristics of this project are narrow and long, and it is built along the river bank. For the narrow river-side foundation pit, its main failure mode is the arc sliding pit bottom uplift failure mode, and its soil uplift is blocked by the opposite side soil and support structure at the same time. At the same time, the narrow and long foundation pit is affected by the upper terrain and water level, and its soil displacement law, support structure force characteristics and deformation characteristics are different from those of the previous wide foundation pits. At present, there are no specific calculation formulas related to the support of narrow foundation pits near urban rivers in the relevant specifications, papers and patents of national construction foundation pits. Therefore, the use of traditional calculation methods does not conform to the actual situation, which is easy to cause safety accidents and economic losses. Summary of the invention

[0003] In view of the shortcomings of the calculation methods in the prior art, the present invention provides a calculation method for the anti-uplift stability of a riverside narrow foundation pit. By considering the blocking effect of the opposite side soil and the supporting structure when the circular arc slides and uplifts, the four parameters of the slope angle and the distance from the river, as well as the force and permeability generated by the river water level change on the foundation pit are introduced into the traditional calculation method to obtain the calculation result of the anti-uplift stability of the riverside narrow foundation pit. Compared with the traditional calculation method, the present invention adds 4 new parameters: the slope angle of the middle and upper soil body outside the pit and the distance from the river, and the force and permeability generated by the river water level change on the foundation pit. Among them, the two parameters of the slope angle of the middle and upper soil body outside the pit and the distance from the river are used to reflect the problem of uneven terrain outside the pit of the riverside narrow foundation pit, and make up for the defect that the traditional calculation method does not consider the terrain factors outside the pit. Among them, the two parameters of the force and permeability generated by the river water level change on the foundation pit are used to reflect the problem that the riverside narrow foundation pit is affected by the river outside the pit. Compared with the traditional calculation method, it has the advantage of considering the factors affecting the river outside the pit.

[0004] To achieve the above-mentioned purpose, the present invention provides a method for calculating and analyzing the stability of a narrow foundation pit near a river. The method for calculating and analyzing the stability of a narrow foundation pit near a river comprises the following steps:

[0005] Step 1: Establish a model of a narrow foundation pit near a river, including slope segment AC, foundation pit straight area segment CD, foundation pit arc area segment DEF, foundation pit arc area segment FG, foundation pit straight area segment GJ, upper load q, upper soil CAPOD area and arc sliding segment soil DEKO area; the intersection point C of the arc sliding surface of the upper soil CAPOD area and the river bank slope, and the height of the river water level from the ground is h w ,

[0006] Among them, when the pile length L ≤ the foundation pit width B, it is defined as a narrow foundation pit;

[0007] Among them, when the pile length L> the foundation pit width B, it is defined as a general foundation pit;

[0008] Among them, the sliding radius of the narrow foundation pit arc is R = B, the center O is located at the lower part of the intersection of the pit bottom and the supporting structure, and the buried depth is O = H + LR, where H is the excavation depth of the foundation pit and L is the length of the pile body;

[0009] Step 2: Based on the established model, according to the blocking effect of the opposite side soil and supporting structure when the narrow foundation pit is uplifted due to circular sliding, the following parameters are introduced as the calculation parameters of the anti-uplift stability calculation and analysis method of the river-side narrow foundation pit according to the terrain factors, including: slope angle α, river distance b, and the force F generated by the change of river water level on the foundation pit. w 2. The penetration force of river water level changes on foundation pits;

[0010] Step 3: According to the model of step 1 and the parameters of step 2, calculate the anti-slip moment MR1 generated by the slope segment AC on the arc sliding surface, calculate the anti-slip moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding, calculate the anti-slip moment MR3 generated by the arc area segment DEF of the foundation pit on the arc sliding, calculate the anti-slip moment MR4 generated by the arc area segment FG of the foundation pit on the arc sliding, calculate the sliding moment MS1 generated by the upper load q at the distance b from the river and the self-weight of the upper soil area CAPOD, calculate the sliding moment MS2 generated by the self-weight of the soil area DEKO of the arc sliding section, calculate the river bank force F W Sliding moment MSW F , the sliding moment MSW of the river on the foundation pit penetration force J f ;

[0011] Step 4: According to the parameters MR1, MR2, MR3, MR4, MS1, MS2, MSW calculated in step 3 F and MSW f , the total anti-sliding moment MR and the total sliding moment MS are calculated, and finally the anti-uplift stability coefficient k of the riverside narrow foundation pit is obtained s .

[0012] The calculation of the anti-sliding moment needs to consider the shear strength of the sliding surface and the passive earth pressure involved; the factors affecting the anti-sliding moment of each surface segment in the model of the riverside narrow foundation pit are as follows:

[0013] The anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface needs to be considered in the formula to introduce the shear strength τ1 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0014] The anti-sliding moment MR2 generated by the straight section CD of the foundation pit on the arc sliding surface needs to be considered in the formula to introduce the shear strength τ2 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0015] The anti-sliding moment MR3 generated by the circular arc section DEF of the foundation pit on the circular arc sliding surface needs to be considered in the formula to introduce the shear strength τ3 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0016] The anti-sliding moment MR4 generated by the circular arc section FG of the foundation pit on the circular arc sliding surface needs to be considered in the formula to introduce the shear strength τ4 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0017] The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil outside the narrow foundation pit near the river, and the calculation formulas for the anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface and the anti-sliding moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding are obtained:

[0018] The anti-sliding moment MR1 generated by the slope segment AC in the upper slope on the arc sliding surface is:

[0019]

[0020]

[0021]

[0022] The anti-sliding moment generated by the straight area CD of the foundation pit against the circular sliding is:

[0023]

[0024] H C =H+LB;

[0025] Where τ1 is the shear strength of the slope section AC, τ2 is the shear strength of the straight area section CD of the foundation pit, t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0026] Among them, according to the blocking effect of the opposite side soil and supporting structure when the narrow foundation pit circular sliding uplifts, the calculation formula of the anti-sliding moment MR3 generated by the circular area section DEF of the foundation pit on the circular sliding and the anti-sliding moment MR4 generated by the circular area section FG of the foundation pit on the circular sliding is obtained:

[0027] The anti-sliding moment generated by the circular arc section DEF of the foundation pit against the circular arc sliding is:

[0028]

[0029] The anti-sliding moment generated by the circular arc section FG of the foundation pit against the circular arc sliding is:

[0030]

[0031] in is the passive earth pressure coefficient;

[0032] The shear strength of the circular arc section DEF of the foundation pit is τ3, the shear strength of the circular arc section FG is τ4, and the t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0033] The sliding moment is mainly provided by the upper load q acting at the distance b from the river, the self-weight of the upper soil area CAPOD, and the self-weight of the circular sliding section soil area DEKO;

[0034] The slope angle α and the distance b from the river can be used to quantitatively calculate the degree of unevenness of the soil outside the narrow foundation pit near the river;

[0035] The other calculation parameters of sliding torque include: γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0036] The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil terrain outside the river-side narrow foundation pit, and the calculation formulas for the sliding moment MS1 generated by the self-weight of the CAPOD area of ​​the upper soil and the sliding moment MS2 generated by the self-weight of the DEKO area of ​​the arc sliding section are obtained:

[0037] The sliding moment generated by the upper load q at the river distance b and the self-weight of the upper soil CAPOD area is:

[0038]

[0039] The sliding moment generated by the self-weight of the DEKO area of ​​the circular sliding section soil:

[0040]

[0041] where γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0042] The two parameters of force and permeability generated by river water level changes on the foundation pit are used to numerically calculate the influence of the river outside the pit on the narrow riverside foundation pit, and then the sliding moment calculation of the area affected by the river is completed; the arc sliding surface and the river bank slope have an intersection C, and the height of the river water level from the ground is h w , from which we can deduce the scope of the river's influence on the river bank:

[0043] CS=(Rb)tan(α)-h w =hh w

[0044] Forces of the river on the riverbank:

[0045]

[0046] The river bank force F W .

[0047] The force F acting on the river bank w Sliding torque:

[0048]

[0049] Sliding moment of river on foundation pit penetration force J:

[0050]

[0051] Among them, γ w It is water heavy.

[0052] In summary, the calculation formula for the anti-uplift stability coefficient of the riverside narrow foundation pit is as follows:

[0053] The expression of the total anti-slip moment MR is:

[0054] MR=MR1+MR2+MR3+MR4+MR5;

[0055] The expression of total sliding moment MS is:

[0056]

[0057] The anti-uplift stability coefficient of the narrow foundation pit near the river is obtained as follows:

[0058]

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. The two parameters of the slope angle of the middle and upper part of the soil outside the pit and the distance from the river reflect the problem of uneven terrain outside the pit when calculating the narrow foundation pit near the river, making up for the defect that the traditional calculation method does not consider the terrain factors outside the pit.

[0061] 2. The two parameters of the slope angle of the middle and upper part of the soil outside the pit and the distance from the river are used to reflect the problem of uneven terrain outside the pit of the narrow foundation pit near the river, and to make up for the defect that the traditional calculation method does not consider the terrain factors outside the pit.

[0062] 3. The two parameters of the slope angle of the middle and upper part of the soil outside the pit and the distance from the river are used to reflect the problem of uneven terrain outside the pit of the narrow foundation pit near the river, and to make up for the defect that the traditional calculation method does not consider the terrain factors outside the pit.

[0063] 4. The two parameters of force and permeability generated by river water level changes on the foundation pit are used to reflect the problem that the calculation of river-side narrow foundation pits is affected by rivers outside the pit. Compared with traditional calculation methods, it has the advantage of considering the influence of rivers outside the pit.

[0064] 5. The two parameters of the slope angle of the upper part of the soil outside the pit and the distance from the river are used to reflect the uneven terrain of the soil outside the pit in the calculation of the river-side narrow foundation pit, and to make up for the defect that the traditional calculation method does not consider the terrain factors outside the pit. Among them, the two parameters of the force and penetration force generated by the change of river water level on the foundation pit are used to reflect the problem that the calculation of the river-side narrow foundation pit is affected by the river outside the pit. Compared with the traditional calculation method, it has the advantage of considering the influence of the river outside the pit. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The figure is a schematic flow chart of a method for calculating the anti-uplift stability of a riverside narrow foundation pit according to the present invention.

[0066] Figure 2 Four parameter schematic diagrams are introduced for a method for calculating the anti-uplift stability of a riverside narrow foundation pit of the present invention.

[0067] Figure 3 It is a schematic diagram of a model of a method for calculating the anti-uplift stability of a riverside narrow foundation pit according to the present invention.

[0068] Figure 4 It is a schematic diagram of a simulation of a riverside narrow foundation pit of the present invention.

[0069] Figure 5 It is a schematic diagram for comparing and verifying a method for calculating the anti-uplift stability of a riverside narrow foundation pit according to the present invention. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0071] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown in the figure, the riverside section AC is a slope. Considering the influence of the upper terrain, the anti-sliding moment is obtained by the shear strength of the slope section AC, the shear strength of the straight area section CD of the foundation pit, the shear strength of the arc area section DEFG of the foundation pit, the passive earth pressure of the straight section GJ, and the ultimate resistance moment M provided by the wall using the limit equilibrium analysis method. h Provided together. Since different material structures and thicknesses of underground walls will affect their ultimate resistance bending moment, which is difficult to determine, the present invention ignores this and uses it as a safety reserve. The sliding moment is mainly provided by the upper load q acting at a distance b from the river, the self-weight of the upper soil area CAPOD, and the self-weight of the circular arc sliding section soil area DEKO. The self-weight of the soil in area KEF offsets the self-weight of the soil in area KFG, and its sliding moment is no longer calculated.

[0072] The model of the narrow foundation pit near the river is established, including the slope segment AC, the foundation pit straight area segment CD, the foundation pit arc area segment DEF, the foundation pit arc area segment FG, the foundation pit straight area segment GJ, the upper load q, the upper soil CAPOD area and the arc sliding segment soil DEKO area; the intersection point C of the arc sliding surface in the upper soil CAPOD area and the river bank slope, and the height of the river water level from the ground is h w ,

[0073] Among them, when the pile length L ≤ the foundation pit width B, it is defined as a narrow foundation pit;

[0074] Among them, when the pile length L> the foundation pit width B, it is defined as a general foundation pit;

[0075] Among them, the sliding radius of the narrow foundation pit arc is R = B, the center O is located at the lower part of the intersection of the pit bottom and the supporting structure, and the buried depth is O = H + LR, where H is the excavation depth of the foundation pit and L is the length of the pile body;

[0076] Step 2: Based on the established model, according to the blocking effect of the opposite side soil and supporting structure when the narrow foundation pit is uplifted due to circular sliding, the following parameters are introduced as the calculation parameters of the anti-uplift stability calculation and analysis method of the river-side narrow foundation pit according to the terrain factors, including: slope angle α, river distance b, and the force F generated by the change of river water level on the foundation pit. w 2. The penetration force of river water level changes on foundation pits;

[0077] Step 3: According to the model of step 1 and the parameters of step 2, calculate the anti-slip moment MR1 generated by the slope segment AC on the arc sliding surface, calculate the anti-slip moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding, calculate the anti-slip moment MR3 generated by the arc area segment DEF of the foundation pit on the arc sliding, calculate the anti-slip moment MR4 generated by the arc area segment FG of the foundation pit on the arc sliding, calculate the sliding moment MS1 generated by the upper load q at the distance b from the river and the self-weight of the upper soil area CAPOD, calculate the sliding moment MS2 generated by the self-weight of the soil area DEKO of the arc sliding section, calculate the river bank force F W Sliding moment MSW F , the sliding moment MSW of the river on the foundation pit penetration force J f ;

[0078] Step 4: According to the parameters MR1, MR2, MR3, MR4, MS1, MS2, MSW calculated in step 3 F and MSW f , the total anti-sliding moment MR and the total sliding moment MS are calculated, and finally the anti-uplift stability coefficient k of the riverside narrow foundation pit is obtained s .

[0079] The calculation of the anti-sliding moment needs to consider the shear strength of the sliding surface and the passive earth pressure involved; the factors affecting the anti-sliding moment of each surface segment in the model of the riverside narrow foundation pit are as follows:

[0080] The anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface needs to be considered in the formula to introduce the shear strength τ1 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0081] The anti-sliding moment MR2 generated by the straight section CD of the foundation pit on the arc sliding surface needs to be considered in the formula to introduce the shear strength τ2 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0082] The anti-sliding moment MR3 generated by the circular arc section DEF of the foundation pit on the circular arc sliding surface needs to be considered in the formula to introduce the shear strength τ3 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0083] The anti-sliding moment MR4 generated by the circular arc section FG of the foundation pit on the circular arc sliding surface needs to be considered in the formula to introduce the shear strength τ4 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0084] The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil outside the narrow foundation pit near the river, and the calculation formulas for the anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface and the anti-sliding moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding are obtained:

[0085] The anti-sliding moment MR1 generated by the slope segment AC in the upper slope on the arc sliding surface is:

[0086]

[0087]

[0088]

[0089] The anti-sliding moment generated by the straight area CD of the foundation pit against the circular sliding is:

[0090]

[0091] H C =H+LB;

[0092] Where τ1 is the shear strength of the slope section AC, τ2 is the shear strength of the straight area section CD of the foundation pit, t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0093] Among them, according to the blocking effect of the opposite side soil and supporting structure when the narrow foundation pit circular sliding uplifts, the calculation formula of the anti-sliding moment MR3 generated by the circular area section DEF of the foundation pit on the circular sliding and the anti-sliding moment MR4 generated by the circular area section FG of the foundation pit on the circular sliding is obtained:

[0094] The anti-sliding moment generated by the circular arc section DEF of the foundation pit against the circular arc sliding is:

[0095]

[0096] The anti-sliding moment generated by the circular arc section FG of the foundation pit against the circular arc sliding is:

[0097]

[0098] in is the passive earth pressure coefficient;

[0099] The shear strength of the circular arc section DEF of the foundation pit is τ3, the shear strength of the circular arc section FG is τ4, and the t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0100] The sliding moment is mainly provided by the upper load q acting at the distance b from the river, the self-weight of the upper soil area CAPOD, and the self-weight of the circular sliding section soil area DEKO;

[0101] The slope angle α and the distance b from the river can be used to quantitatively calculate the degree of unevenness of the soil outside the narrow foundation pit near the river;

[0102] The other calculation parameters of sliding torque include: γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0103] The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil terrain outside the river-side narrow foundation pit, and the calculation formulas for the sliding moment MS1 generated by the self-weight of the CAPOD area of ​​the upper soil and the sliding moment MS2 generated by the self-weight of the DEKO area of ​​the arc sliding section are obtained:

[0104] The sliding moment generated by the upper load q at the river distance b and the self-weight of the upper soil CAPOD area is:

[0105]

[0106] The sliding moment generated by the self-weight of the DEKO area of ​​the circular sliding section soil:

[0107]

[0108] where γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

[0109] The two parameters of force and permeability generated by river water level changes on the foundation pit are used to numerically calculate the influence of the river outside the pit on the narrow riverside foundation pit, and then the sliding moment calculation of the area affected by the river is completed; the arc sliding surface and the river bank slope have an intersection C, and the height of the river water level from the ground is h w , from which we can deduce the scope of the river's influence on the river bank:

[0110] CS=(Rb)tan(α)-h w =hh w

[0111] Forces of the river on the riverbank:

[0112]

[0113] The river bank force F W .

[0114] The force F acting on the river bank w Sliding torque:

[0115]

[0116] Sliding moment of river on foundation pit penetration force J:

[0117]

[0118] Among them, γ w It is water heavy.

[0119] In summary, the calculation formula for the anti-uplift stability coefficient of the riverside narrow foundation pit is as follows:

[0120] The expression of the total anti-slip moment MR is:

[0121] MR=MR1+MR2+MR3+MR4+MR5;

[0122] The expression of total sliding moment MS is:

[0123]

[0124] The anti-uplift stability coefficient of the narrow foundation pit near the river is obtained as follows:

[0125] Specific embodiments

[0127] The design conditions are as follows: the foundation pit depth is 7m, the foundation pit excavation width is 8m, the insertion depth is 9m, the soil weight is 18KN / m3, the water weight is 10KN / m3, the soil cohesion is 10kPa, the internal friction angle is 20°, the distance to the river is 4m, the slope angle is 45°, the foundation pit width is 8m, and the water level difference (i.e., the difference between the ground elevation and the water surface elevation) is introduced for calculation. The calculation comparison results of the method provided by the present invention and the standard method are as follows: Figure 5 As shown. Figure 5 It can be seen that the k obtained by this method is s The values ​​are all greater than the standard values. It can be seen that in actual projects, the anti-uplift stability coefficient of the riverside narrow foundation pit calculated by this method is higher than that of the traditional standard method, and the corresponding riverside narrow foundation pit has better stability. With better stability, the actual length of the pile driven into the foundation pit can be shortened, which is conducive to saving engineering costs.

[0128] The present invention has the following advantages:

[0129] 1. The two parameters of the slope angle of the middle and upper part of the soil outside the pit and the distance from the river reflect the problem of uneven terrain outside the pit when calculating the narrow foundation pit near the river, making up for the defect that the traditional calculation method does not consider the terrain factors outside the pit.

[0130] 2. The two parameters of force and permeability generated by river water level changes on the foundation pit are used to reflect the problem that the calculation of river-side narrow foundation pits is affected by rivers outside the pit. Compared with traditional calculation methods, it has the advantage of considering the influence of rivers outside the pit.

[0131] 3. This method is applicable to narrow foundation pit projects near rivers and along river banks. By considering the blocking effect of the soil and supporting structure on the opposite side of the narrow foundation pit, four parameters are introduced to consider terrain-related factors, namely slope angle and distance from the river, as well as the force and penetration force generated by river water level changes on the foundation pit. The calculation formula can be used to design and calculate the anti-uplift stability of narrow foundation pits near inland rivers, so as to achieve the purpose of safe calculation and design, in line with actual conditions and economical application, and solve the problem of inconsistent results and economic waste caused by design and calculation according to current specifications.

[0132] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for calculating and analyzing the stability of a narrow foundation pit near a river, characterized in that: The method comprises the following steps: Step 1: Establish a model of a narrow foundation pit near a river, including slope segment AC, foundation pit straight area segment CD, foundation pit arc area segment DEF, foundation pit arc area segment FG, foundation pit straight area segment GJ, upper load q, upper soil CAPOD area and arc sliding segment soil DEKO area; the intersection point C of the arc sliding surface of the upper soil CAPOD area and the river bank slope, and the height of the river water level from the ground is h w , Among them, when the pile length L≤the foundation pit width B, it is defined as a narrow foundation pit; Among them, the sliding radius of the narrow foundation pit arc is R = B, the center O is located at the lower part of the intersection of the pit bottom and the supporting structure, and the buried depth is O = H + LR, where H is the excavation depth of the foundation pit and L is the length of the pile body; Step 2: Based on the established model, the following parameters are introduced as the calculation parameters of the anti-uplift stability calculation and analysis method of the narrow foundation pit near the river, including: slope angle α, distance from the river b, force F exerted by river water level changes on the foundation pit w , the permeability J generated by the change of river water level on the foundation pit; Step 3: According to the model of step 1 and the parameters of step 2, calculate the anti-slip moment MR1 generated by the slope segment AC on the arc sliding surface, calculate the anti-slip moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding, calculate the anti-slip moment MR3 generated by the arc area segment DEF of the foundation pit on the arc sliding, calculate the anti-slip moment MR4 generated by the arc area segment FG of the foundation pit on the arc sliding, calculate the sliding moment MS1 generated by the upper load q at the distance b from the river and the self-weight of the upper soil area CAPOD, calculate the sliding moment MS2 generated by the self-weight of the soil area DEKO of the arc sliding section, calculate the river bank force F W Sliding moment MSW F , the sliding moment MSW of the river on the foundation pit penetration force J f ; Step 4: According to the parameters MR1, MR2, MR3, MR4, MS1, MS2, MSW calculated in step 3 F and MSW f , the total anti-sliding moment MR and the total sliding moment MS are calculated, and finally the anti-uplift stability coefficient k of the riverside narrow foundation pit is obtained s .

2. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 1 is characterized in that: The calculation of the anti-sliding moment needs to consider the shear strength of the sliding surface and the passive earth pressure involved; among them, the factors affecting the anti-sliding moment of each surface segment in the model of the riverside narrow foundation pit are as follows: The anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface is introduced into the shear strength τ1 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle; The anti-sliding moment MR2 generated by the straight section CD of the foundation pit on the arc sliding surface is introduced into the shear strength τ2 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle; The anti-sliding moment MR3 generated by the circular arc section DEF of the foundation pit on the circular arc sliding surface is introduced to the shear strength τ3 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle; The anti-sliding moment MR4 generated by the circular arc section FG of the foundation pit on the circular arc sliding surface is introduced into the shear strength τ4 and γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

3. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 2 is characterized in that: The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil terrain outside the narrow foundation pit near the river, and the calculation formulas for the anti-sliding moment MR1 generated by the slope segment AC on the arc sliding surface and the anti-sliding moment MR2 generated by the straight area segment CD of the foundation pit on the arc sliding are obtained: The anti-sliding moment MR1 generated by the slope segment AC in the upper slope on the arc sliding surface is: The anti-sliding moment generated by the straight area CD of the foundation pit against the circular sliding is: H C =H+L-B; Where τ1 is the shear strength of the slope section AC, τ2 is the shear strength of the straight area section CD of the foundation pit, t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

4. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 2 is characterized in that: According to the blocking effect of the opposite side soil and supporting structure when the narrow foundation pit circular sliding uplifts, the calculation formula of the anti-sliding moment MR3 generated by the circular area section DEF of the foundation pit on the circular sliding and the anti-sliding moment MR4 generated by the circular area section FG of the foundation pit on the circular sliding is obtained: The anti-sliding moment generated by the circular arc section DEF of the foundation pit against the circular arc sliding is: The anti-sliding moment generated by the circular arc section FG of the foundation pit against the circular arc sliding is: in is the passive earth pressure coefficient; The shear strength of the circular arc section DEF of the foundation pit is τ3, the shear strength of the circular arc section FG is τ4, and the t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

5. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 1 is characterized in that: The sliding moment is mainly provided by the upper load q acting at the distance b from the river, the self-weight of the upper soil area CAPOD, and the self-weight of the soil area DEKO in the circular sliding section; The slope angle α and the distance b from the river can be used to quantitatively calculate the degree of unevenness of the soil outside the narrow foundation pit near the river; The sliding moment calculation parameters also include: γ t It is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle.

6. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 5 is characterized in that: The slope angle α and the distance b from the river are used to quantitatively calculate the unevenness of the soil terrain outside the river-side narrow foundation pit, and the calculation formulas for the sliding moment MS1 generated by the deadweight of the CAPOD area of ​​the upper soil and the sliding moment MS2 generated by the deadweight of the DEKO area of ​​the arc sliding section are obtained: The sliding moment generated by the upper load q at the river distance b and the self-weight of the upper soil CAPOD area is: The sliding moment generated by the self-weight of the soil DEKO area in the arc sliding section: where γ t is the weight of soil; h is the distance between the contact point between the sliding surface and the slope and the top of the slope; b is the distance to the river; q is the upper load; k is the distance between the sliding surface and the slope and the top of the slope; a is the active earth pressure coefficient; c is the effective internal cohesion; is the effective internal friction angle; α is the slope angle, and δ is the angle between the center of the circle in the model and the lower soil layer.

7. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 5 is characterized in that: The two parameters of force and penetration force generated by river water level changes on the foundation pit are used to numerically calculate the influence of the river outside the pit on the narrow river foundation pit, and then the sliding moment calculation of the area affected by the river is completed; there is an intersection C between the arc sliding surface and the river bank slope, and the height of the river water level from the ground is h w , from which we can deduce the scope of the river's influence on the river bank: CS=(Rb)tan(α)-h w =hh w Forces of the river on the riverbank: The river bank force is F W , ρ is the density of river water, and g is the acceleration due to gravity.

8. The method for calculating and analyzing the anti-uplift stability of a narrow foundation pit near a river according to claim 7 is characterized in that: The force F exerted by the river on the riverbank w Sliding torque: Sliding moment of river on foundation pit penetration force J: Among them, γ w It is water heavy.

9. A method for calculating and analyzing the anti-uplift stability of a riverside narrow foundation pit according to any one of claims 1 to 8, characterized in that: The calculation formula of the anti-uplift stability coefficient of the riverside narrow foundation pit is as follows: The expression of the total anti-slip moment MR is: MR=MR1+MR2+MR3+MR4+MR5; The expression of total sliding moment MS is: The anti-uplift stability coefficient of the narrow foundation pit near the river is obtained as follows:

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