A seepage cutoff well drainage system and a preparation method thereof

Abstract

The present application relates to the technical field of anti-floating dewatering of underground engineering, and particularly relates to a cutoff well drainage system and a preparation method. The cutoff well drainage system comprises a closed water-stopping curtain made around the outer wall of a basement, the water-stopping curtain entering an aquiclude, a cutoff well circle formed by a circle of cutoff wells along the inner side of the basement outer wall bottom plate, and the cutoff pumping wells and the cutoff self-flowing wells being arranged alternately. The geometric parameters and the single-well flow rate of each dewatering unit cutoff pumping well are determined first, and then the spacing and the total number of adjacent cutoff pumping wells are determined through calculation, and the cutoff wells are arranged in the permeable layer. The groundwater around the bottom end of the water-stopping curtain is intercepted by the cutoff wells, and the groundwater in the cutoff wells is pumped out, so that the groundwater level is controlled below the anti-floating water level. The cutoff pumping wells and the cutoff self-flowing wells are connected through overflow drainage channels. According to the technical scheme of the present application, the water-stopping curtain and the cutoff wells are combined to form a double water-stopping barrier, thereby improving the reliability of the basement anti-floating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anti-floating of underground engineering, and particularly relates to a cut-off well drainage system and a preparation method. BACKGROUND

[0002] The anti-floating methods for urban buildings and underground engineering mainly include a passive anti-floating method of setting anti-floating piles or anti-floating anchor rods and an active anti-floating method of lowering the underground water level. When the passive anti-floating method is used, if the underground water level exceeds the anti-floating defense water level, the building or structure will probably float. When the active anti-floating method is used, as long as the drainage capacity is enough, the probability that the underground water level exceeds the anti-floating defense water level is low. Therefore, the active anti-floating method is safer.

[0003] The active anti-floating method of lowering the underground water level is used, for example, a patent CN105569095B discloses a cut-off drainage pressure reduction anti-floating system. A cylindrical reinforced concrete frame is used as a skeleton for bearing the water and soil lateral pressure. The reinforced concrete frame space is filled with sand-free concrete blocks as a drainage body to lower and control the underground water level. The sand-free concrete blocks do not bear the water and soil lateral pressure. However, the sand-free concrete blocks directly contact the soil. If the sand-free concrete blocks need to be replaced due to blockage, the old blocks are removed, and the soil is at risk of collapse. A patent CN103061351B discloses a device for preventing the basement floor from rising and seeping water. A self-seepage water collecting pit drainage method is used. If the underground water level rises at a speed greater than the seepage speed to the water collecting pit, the basement will be at risk of floating. These patents have a common problem that how to arrange and calculate the cut-off well or water collecting pit for an irregularly shaped basement. Another disadvantage is that the cut-off well construction is first formed into a hole and then the well tube is lowered. When the hole is drilled, a mud wall protection process is used to generate a thick mud skin on the hole wall, which hinders the seepage efficiency of the underground water to the cut-off well. The hole needs to be punched, the mud needs to be replaced, the well tube needs to be lowered, the mud needs to be diluted, the filter material needs to be backfilled, the water needs to be stopped, the hole needs to be sealed, and the well needs to be washed. The process is complex. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a cut-off well drainage system and a preparation method. The cut-off well construction method uses a sinking method while the soil is being removed. The filling or bottom sealing water permeable material of the cut-off well is convenient to replace, and no collapse risk is generated during replacement. For irregularly shaped basements, the cut-off well drainage system can solve the problems of division of regional drainage units, arrangement distance of cut-off wells and calculation of single well water inflow for different thicknesses of water permeable layers and different loads in different regions in the site.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] In a first aspect, the present disclosure provides a cut-off well drainage system, comprising:

[0007] A waterproof curtain is arranged along the periphery of the basement outer wall, a seepage interception well is arranged around the basement floor, an overflow drainage channel, a water pump and a drainage pipe are arranged correspondingly; the seepage interception well comprises the seepage interception pumping well and the seepage interception self-flowing well, the seepage interception pumping well and the seepage interception self-flowing well are arranged alternately along the inner periphery of the basement outer wall; the seepage interception pumping well and the seepage interception self-flowing well are located in the underground water-permeable layer, the depth of the seepage interception pumping well is greater than that of the seepage interception self-flowing well;

[0008] The overflow drainage channel is arranged below the basement floor; the seepage interception pumping well and the seepage interception self-flowing well are communicated through the overflow drainage channel, the seepage interception pumping well passes through the overflow drainage channel and the basement floor in sequence, and the seepage interception self-flowing well is located below the overflow drainage channel;

[0009] The water pump and part of the drainage pipe are located in the seepage interception pumping well, and the drainage pipe discharges the underground water in the seepage interception pumping well to the ground through the water pump.

[0010] In some embodiments, the seepage interception pumping well and the seepage interception self-flowing well are in a hamburger structure, the hamburger structure comprises an outer cylinder, an inner cylinder, a well shoe and an isolation bottom plate;

[0011] The first water-permeable filling material is arranged between the outer cylinder and the inner cylinder, the well shoe is located below the first water-permeable filling material arranged between the outer cylinder and the inner cylinder, and the well shoe is in contact with the side wall of the outer cylinder and the inner cylinder;

[0012] The isolation bottom plate is used for closing the bottom opening of the inner cylinder, the second water-permeable filling material is arranged below the isolation bottom plate, and the second water-permeable filling material is in contact with the well shoe.

[0013] In some embodiments, the cross section of the well shoe is in the shape of an inverted triangular horn, and the bottom end of the well shoe is in the shape of a ring-shaped cutting edge.

[0014] In some embodiments, the outer cylinder is a reinforced cage skeleton plastic cylinder, and the inner cylinder is formed by binding a steel wire mesh with a reinforced cage.

[0015] A plurality of stiffening ribs are arranged between the outer cylinder and the inner cylinder, and a honeycomb-shaped water-permeable hole is arranged on the arm of the outer cylinder.

[0016] In some embodiments, the overflow drainage channel is arranged in the shape of a rectangular overflow drainage channel or a circular overflow drainage pipe.

[0017] In some embodiments, the well cover of the seepage interception pumping well is flush with the top surface of the basement floor.

[0018] In a second aspect, the present disclosure also provides a preparation method of a cutoff well drainage system, comprising:

[0019] forming a closed water-stop curtain around the outer wall of the basement;

[0020] dividing the contour of the basement into multiple dewatering units and determining the number of cutoff wells for each dewatering unit; the cutoff wells include cutoff pumping wells and cutoff gravity-flow wells;

[0021] arranging cutoff wells and overflow drainage channels corresponding to the basement floor; the cutoff wells include cutoff pumping wells and cutoff gravity-flow wells, which are arranged alternately along the inner periphery of the outer wall of the basement; the cutoff pumping wells and the cutoff gravity-flow wells are located in the underground permeable layer, and the depth of the cutoff pumping wells is greater than that of the cutoff gravity-flow wells;

[0022] installing a water pump and a drainage pipe in the cutoff pumping well, and connecting the drainage pipe to a ground drainage ditch;

[0023] wherein the overflow drainage channel is arranged below the basement floor; the cutoff pumping wells and the cutoff gravity-flow wells are communicated through the overflow drainage channel, the cutoff pumping wells pass through the overflow drainage channel and the basement floor in sequence, and the cutoff gravity-flow wells are located below the overflow drainage channel.

[0024] Further, a circle of cutoff wells is arranged along the inner periphery of the basement floor, which is at a distance of not less than 1.0 m from the outer wall of the basement, and the dewatering units are divided according to the contour of the basement, the thickness distribution of the permeable layer, the self-weight and load distribution of the superstructure, etc., and the division of the dewatering units and the calculation of the cutoff wells are determined according to the following steps.

[0025] (1) the irregular polygon contour of the basement is equivalent to a circle

[0026] First, the irregular polygon basement is equivalent to a rectangle, and the length and width of the equivalent rectangle are determined according to the conditions that the perimeter is equal and the ratio of the maximum length a max of the polygon to the maximum width b max is equal to the length-width ratio of the rectangle: ; wherein, L C is the contour perimeter of the irregular polygon basement (unit: m), is the side length of the irregular polygon (M is the number of polygon sides), a is the long side length of the rectangular contour (unit: m), b is the short side length (unit: m), a max is the maximum outer contour length of the irregular polygon (unit: m), and b max is the maximum outer contour width of the irregular polygon (unit: m).

[0027] When the rectangular profile of the basement is equivalent to a circle, the equivalent circle radius can be calculated as follows:

[0028]

[0029] (2) Precipitation unit division

[0030] According to the thickness distribution of the permeable layer, the self-weight and load distribution of the upper structure, and other conditions, the structure is divided into m precipitation units by a number of intersecting lines passing through the centroid of the structure. The soil layer distribution in each precipitation unit is relatively uniform with the self-weight and load distribution of the upper structure. Suction extraction wells and interception artesian wells are uniformly arranged in the precipitation units. The interception artesian wells function to assist the collection of groundwater into the suction extraction wells and do not participate in the calculation of drainage. The spacing of the interception wells in different precipitation units is different.

[0031] (3) Calculation of the number of suction extraction wells

[0032] After the irregular shape is equivalent to a circular structure, the outflow boundary length of the i-th (i = 1, 2,..., m) precipitation unit remains unchanged, and the central angle is :

[0033]

[0034] where L i is the outflow boundary length of the i-th precipitation unit (unit: m).

[0035] Taking a unit width circular ring seepage field analysis, the inside and outside seepage fields of the i-th precipitation unit are analyzed. The outside seepage field is in a confined mode, and the water level along the path decreases from h0 (unit: m) to the water level h 1i outside the cutoff curtain (unit: m); the inside seepage field is solved by an analytical solution, and the water level along the path decreases from the cutoff curtain inside water level h 2i (unit: m) to the interception well water level h wi (unit: m); the inside and outside seepage fields are connected in series by the flow around the cutoff curtain bottom, and the inside and outside water head losses of the cutoff curtain are h 1i -h 2i (unit: m).

[0036] By pre-determining the radius r wi of the interception extraction well (unit: m), the well water level h wi (unit: m), and the single well flow rate q i (unit: m 3 / d), the number of arranged interception extraction wells n i is determined by the following formula:

[0037]

[0038] where,

[0039]

[0040] wherein h0 is the initial water level of the site (unit: m), R0 is the influence radius of the seepage zone (unit: m), wherein R0 = (2~3)R, L C is the contour perimeter of the basement (unit: m), D is the thickness of the waterproof curtain (unit: m), r is the distance between the interception well and the waterproof curtain (unit: m); within the i-th precipitation unit, k 1i is the permeability coefficient of the strong permeable layer (unit: m / d), M 0i and M 1i are the thicknesses of the basement bottom and the strong permeable layer outside the basement (unit: m), k i and M i are the permeability coefficient (unit: m / d) and the thickness (unit: m) of the weak permeable layer (relative aquifuge), d i is the thickness of the weak permeable layer at the bottom of the waterproof curtain (unit: m), ξ1, ξ2 and ξ3 are dimensionless resistance coefficients, wherein ξ3 is related to n i .

[0041] The number of interception self-flowing wells arranged is equal to the number of interception pumping wells arranged.

[0042] (4) Anti-floating safety checking

[0043] By adjusting the interception well parameters n i , r wi , h wi , q i , the water level inside the waterproof curtain (unit: m) should be less than the anti-floating prevention water level (unit: m). The arrangement of the interception well in each precipitation unit can be calculated and determined according to the thickness distribution of the permeable layer, the self-weight and load distribution of the upper structure, etc.

[0044] Further, the arrangement of the interception well converts the basement from an irregular polygon with equal perimeter to a rectangle and then to a circular conformal mapping conversion according to the following steps:

[0045] (1) After the conformal transformation of the composite graph, the conformal mapping of the rectangle ABCD on the z plane to the circle on the w plane is obtained.

[0046] (2) Conformal mapping transformation calculation, conformal mapping function of the rectangle and the circle:

[0047]

[0048] wherein γ is determined by the aspect ratio a / b of the rectangle:

[0049]

[0050] In the formula, sn is a Jacobian elliptic function, K(λ) is the first kind of complete elliptic integral, λ is its modulus, λ in the above two formulas is 1 / γ 2 or , ζ is an intermediate auxiliary plane variable, i is an imaginary unit, and γ is a dimensionless physical quantity corresponding to the coordinate of the auxiliary point.

[0051] (3) The angle between the connecting line of the corner points A, B, C and D and the real axis

[0052]

[0053] In the formula, Im(w) is the imaginary part of the complex number w, and Re(w) is the real part of the complex number w. The angle and the value of the length-width ratio a / b of the rectangle, the larger the value of a / b, the more "flat" the rectangle is, the smaller the value is. When a / b=1.0 (the rectangle is a square), there is =π / 4; when a / b>4.0, <0.008 (0.46°).

[0054] The conformal mapping of the rectangle ABCD and the unit circle has uniqueness, when the value of the length-width ratio a / b is certain, the coordinates of the corner points A, B, C and D falling on the unit circle are uniquely determined.

[0055] Compared with the prior art, the present application has the following beneficial effects:

[0056] (1) The well bottom of the cut-off well is an open structure, the cut-off well sinks by self-weight while the soil at the well bottom is taken, mud protection wall process for drilling into a hole is not used, there is no hole wall mud skin, the cut-off well has high permeation efficiency, and the construction process is less.

[0057] (2) The water permeable concrete prefabricated block of the cut-off well has strong water permeability, when the prefabricated block is blocked after long-term operation, it can be conveniently replaced or flushed with a high-pressure water gun, so that the permeability of the filling material is ensured not to be reduced. Since the outer cylinder of the cut-off well is a steel cage skeleton plastic cylinder, when the water permeable filling material is replaced, the outer cylinder structure bears the surrounding water and soil pressure, and there is no risk of hole wall collapse.

[0058] (3) The outer cylinder of the cut-off well is a steel cage skeleton plastic cylinder, the plastic outer skin has a rust-proof protection effect on the outer steel cage bearing water and soil pressure, and the durability of the cut-off well is improved.

[0059] (4) The present application divides the construction site into dewatering units, uses a conformal mapping conversion method to convert an arbitrary shape basement into a circularly arranged cut-off well calculation, simplifies the three-dimensional numerical calculation problem of a complex seepage field into an analytical solution, and greatly improves the calculation efficiency. BRIEF DESCRIPTION OF DRAWINGS ​

[0060] Figure 1 Layout of the cut-off well;

[0061] Figure 2 Sectional view of the cut-off well;

[0062] Figure 3 Principle diagram of the cut-off well for controlling groundwater level;

[0063] Figure 4 Sectional view of the cut-off well;

[0064] Figure 5 Projection view of the cut-off well;

[0065] Figure 6 Welding sectional view of the inner and outer tubes and the well shoe;

[0066] Figure 7 Three-dimensional view of the inner and outer tubes of the cut-off well;

[0067] Figure 8 Three-dimensional view of the plastic tube template supported by the reinforcement cage framework;

[0068] Figure 9 Large-scale view of the installation and fixation of the precast bottom plate of the pervious concrete;

[0069] Figure 10 Sectional view of the rectangular overflow drainage channel;

[0070] Figure 11 Sectional view of the circular overflow drainage pipe;

[0071] Figure 12 Schematic diagram of the joint of the circular overflow drainage pipe;

[0072] Figure 13 Schematic diagram of the division of the dewatering unit;

[0073] Figure 14 Schematic diagram of the unit width circular ring seepage field of the i-th dewatering unit;

[0074] Figure 15 Schematic diagram of the conformal transformation process from rectangular to circular;

[0075] Figure 16 Schematic diagram of the relationship between the included angle and the value of the rectangular length-width ratio a / b.

[0076] The components include: 1. Basement floor slab; 2. Intercepting pumping well; 4. Intercepting gravity flow well; 5. Water pump; 6. Rectangular overflow drainage channel; 7. Circular overflow drainage pipe; 101. Basement exterior wall; 102. Overflow drainage channel; 103. Water-stop curtain; 201. Outer cylinder; 202. Reinforcing cage; 203. Well shoe; 204. Stiffening rib; 205. First permeable filling material; 206. Well cover; 207. Honeycomb permeable holes; 208. Weld; 209. Wire mesh. 301. Second permeable filling material; 501. Drainage pipe; 601. Isolation base plate; 602. Permeable concrete precast side plate; 701. Convex joint outer steel plate; 702. Concave joint outer steel plate; 2011. Outer cylinder steel cage skeleton; 2012. Outer formwork; 2013. Outer formwork hoop; 2014. Inner formwork; 2015. Inner formwork hoop; 2031. Bolt hole; 2032. Bolt; 6010. Drainage base plate; 6020. Drainage side plate. Detailed Implementation

[0077] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0078] like Figures 1 to 16 As shown, a seepage interception well drainage system includes: a water-stopping curtain 103 set along the perimeter of the basement exterior wall 101, seepage interception wells arranged corresponding to the basement floor slab 1, an overflow drainage channel 102, a water pump 5, and a drainage pipe 501; the seepage interception wells include seepage interception pumping wells 2 and seepage interception gravity flow wells 4, which are arranged alternately along the inner perimeter of the basement exterior wall 101, forming a seepage interception well ring; the spacing between adjacent seepage interception wells and the single well inflow rate are determined by calculation based on soil layer thickness, permeability, etc., and the seepage interception wells are located in the permeable layer of the basement; groundwater seeping around the bottom of the water-stopping curtain 103 is intercepted by the seepage intercepting pumping wells 2, and the seepage intercepting pumping wells 2 pump out the groundwater seeping around the water-stopping curtain, and the groundwater exceeding the design flood level is discharged to the ground surface, and the double seepage interception barrier ensures that the groundwater level is controlled below the design flood level.

[0079] Intercepting pumping well 2 and intercepting gravity flow well 4 can have a hamburger structure, such as... Figure 4 and Figure 5 As shown, it can also be a double-layer structure. The hamburger structure consists of an outer cylinder 201, an inner cylinder, a first permeable filling material 205, a well shoe 203, and an isolation base plate 601. The first permeable filling material 205 is located between the outer cylinder 201 and the inner cylinder. In some embodiments, the seepage intercepting pumping well 2 and the seepage intercepting gravity flow well 4 can also adopt a double-layer structure. When a double-layer structure is adopted, the first permeable filling material 205 is made of precast arc-shaped permeable concrete blocks, which are constructed by staggered splicing, and the inner cylinder is eliminated.

[0080] The first water-permeable filling material 205 can be a water-permeable concrete prefabricated block, or can be coarse sand and round gravel. When the filling material is blocked, a high-pressure water gun can be used for flushing or replacement.

[0081] The outer cylinder 201 of the interception well can be a reinforced cage skeleton plastic cylinder or a mesh-permeable water-permeable steel cylinder, and the inner cylinder is formed by binding the steel wire mesh 209 to the reinforced cage 202. The stiffening ribs 204 are arranged between the outer cylinder 201 and the inner cylinder, and the stiffening ribs 204 can be welded by steel plates or steel bars.

[0082] Specifically, the manufacturing method of the interception well is as shown in Figure 6 The outer cylinder 201 of the interception well is a reinforced cage skeleton plastic cylinder, and the length of the interception well is equal to the length of the reinforced cage skeleton plastic cylinder plus the length of the well shoe 203. The outer cylinder 201 is a reinforced cage skeleton plastic cylinder or a steel cylinder, and the outer cylinder 201 is provided with honeycomb water-permeable holes 207 on the arms. The inner cylinder is composed of the reinforced cage 202 and the steel wire mesh 209, and the longitudinal reinforcement of the inner cylinder is the skeleton reinforcement, and the circumferential reinforcement is the circular stirrup. The number of stiffening ribs 204 arranged between the inner and outer cylinders is not less than 3, and the flared well shoe 203 is welded at the bottom of the inner and outer cylinders. The inner cylinder can also be a steel cylinder or a plastic cylinder provided with water-permeable holes.

[0083] The manufacturing method of the reinforced cage skeleton plastic cylinder is as shown in Figure 7 and Figure 8 First, the outer cylinder reinforced cage 2011 is processed by welding the longitudinal skeleton reinforcement and the circular stirrup. The outer formwork 2012 and the inner formwork 2014 are bound on the inner and outer sides of the outer cylinder reinforced cage, and the inner formwork hoop 2015 and the outer formwork hoop 2013 are installed. The plastic is poured into the formwork after being heated and melted, and the formwork is removed after cooling. Small holes are drilled on the side wall of the reinforced cage plastic cylinder to form honeycomb water-permeable holes 207.

[0084] Specifically, the well shoe 203 of the interception well is in the shape of an inverted triangular flared mouth, the bottom end of the well shoe 203 is a circular cutting edge, the diameter of the well shoe 203 is slightly larger than that of the outer cylinder 201, and the interception well sinks by using its own weight when taking soil at the bottom.

[0085] Specifically, as shown in Figure 9 The well bottom of the interception well is an open structure. After the interception well is sunk in place, the well bottom is closed with an isolation bottom plate 601. The isolation bottom plate 601 can be a water-permeable concrete prefabricated bottom plate, which is made in the shape of a circle slightly smaller than the inner diameter of the well shoe 203. The lower part of the isolation bottom plate 601 is filled with a second water-permeable filling material 301, such as gravel, crushed stone, or coarse sand. The second water-permeable filling material 301 is in contact with the well shoe 203, and is used to prevent mud from flowing into the interception well. When the interception well is blocked after long-term use, a high-pressure water gun can be used for flushing or replacement of the isolation bottom plate 601 and the second water-permeable filling material 301.

[0086] The side wall of the bottom of the interception well is pre-drilled with no less than 4 bolt holes 2031 at the same height, as shown in the drawings. Figure 9 The isolation bottom plate 601 is installed at the bottom end of the interception well, which can be a water permeable concrete prefabricated bottom plate, and then the bolt 2032 is inserted into the bolt hole 2031 of the side wall of the interception well for fixation.

[0087] Specifically, as shown in Figure 10 , Figure 11 and Figure 12 , the overflow drainage channel 102 can adopt a rectangular overflow drainage channel 6 or a circular overflow drainage pipe 7. The rectangular overflow drainage channel 6 is composed of a drainage bottom plate 6010 and a drainage side plate 6020, both of which are formed by water permeable concrete prefabrication. The circular overflow drainage pipe 7 is prefabricated by water permeable concrete, one end of which is made into a convex joint wrapped with a steel plate 701, and the other end is made into a concave joint wrapped with a steel plate 702. The circular overflow drainage pipe 7 is connected in a socket way when lengthened, which is convenient for construction.

[0088] The overflow drainage channel 102 is set below the bottom surface of the basement floor 1, and the elevation of the anti-floating water level is determined to meet the requirement that the underground water overflowing from the interception and flow well 4 at high water level flows into the interception and pumping well 2 and is pumped to the ground by the water pump 5, so that the underground water level is controlled below the designed height.

[0089] Specifically, the depth of the interception and pumping well 2 is greater than that of the interception and flow well 4, the interception and pumping well 2 penetrates through the basement floor 1, and the interception and flow well 4 is located below the overflow drainage channel 102. The interception and pumping well 2 and the interception and flow well 4 are communicated through the overflow drainage channel 102.

[0090] Specifically, the preparation method of the interception well drainage system includes the following implementation steps:

[0091] S1, on the outside of the basement outer wall 101, a water stop curtain 103 is constructed, which surrounds the basement outer wall 101 and forms a closed water stop curtain 103;

[0092] S2, a circle of interception and pumping well 2 and interception and flow well 4 are constructed at a distance of no less than 1.0m between the basement floor 1 and the basement outer wall 101.

[0093] S3, a water pump 5 and a drainage pipe 501 are installed in the interception and pumping well 2, and a well cover 206 is covered, and the drainage pipe 501 is connected to the ground drainage ditch.

[0094] During the construction of the basement and in normal use, when the underground water level exceeds the designed water level, the water pump 5 is automatically started to pump water.

[0095] Specifically, a ring of cutoff wells is arranged around the inner perimeter of the basement floor slab, with a distance of no less than 1.0m from the basement exterior wall. The dewatering units are divided according to the basement outline, the distribution of the permeable layer thickness, the self-weight of the superstructure, and the load distribution. The division of dewatering units and the calculation of cutoff wells are determined according to the following steps.

[0096] (1) The irregular polygonal outline of the basement is equivalent to a circle.

[0097] like Figure 13 As shown, the irregular polygonal basement is first equivalent to a rectangle, based on the fact that the perimeters are equal and the maximum length 'a' of the polygon is the largest. max and maximum width b max The condition that the aspect ratio equals the length-to-width ratio of a rectangle determines the length and width of the equivalent rectangle:

[0098] (1)

[0099] in, At this time L C The perimeter of the irregular polygonal basement (in meters). Let M be the side length of the irregular polygon (in meters) (where M is the number of sides of the polygon), a be the length of the longer side of the rectangle (in meters), and b be the length of the shorter side (in meters). max b is the maximum outer contour length of the irregular polygon (in meters). max The maximum outer contour width of the irregular polygon (unit: m).

[0100] When the rectangular outline of the basement is equivalent to a circle, the radius R of the equivalent circle can be calculated using the following formula:

[0101] (2)

[0102] (2) Division of precipitation units

[0103] Based on the distribution of permeable layer thickness, the self-weight of the superstructure, and the load distribution, the interior of the structure is divided into m rainwater units by several intersecting lines passing through the centroid of the structure, such as... Figure 13 As shown, the soil layer distribution and the distribution of the superstructure's self-weight and load are relatively uniform within each dewatering unit. Cut-off wells are evenly arranged within the dewatering unit, and the spacing between the cut-off wells varies between different dewatering units.

[0104] (3) Calculation of the number of seepage interception and pumping wells

[0105] After equating the irregular shape to a circular structure, the inrush boundary length of the i-th (i=1,2,…,m) precipitation unit remains unchanged, while its central angle remains constant. for:

[0106] (3)

[0107] wherein L i is the length of the water inflow boundary of the i-th precipitation unit (unit: m).

[0108] Taking the unit width circular ring seepage field analysis, the inside and outside seepage fields of the i-th precipitation unit are shown in FIG. 1. Figure 14 The outside is in the confined mode, and the water level along the path decreases from h0to the water level h 1i outside the water stop curtain (unit: m); the inside seepage field is solved according to the analytical solution, and along the path, the water level decreases from the water level h 2i inside the water stop curtain to the water level h wi of the seepage well (unit: m); the inside and outside seepage fields are connected in series by the flow through the bottom of the water stop curtain, and the water head loss h 1i -h 2i of the water stop curtain inside and outside (unit: m).

[0109] For the outside seepage field, the water head loss (unit: m) along the path is:

[0110] (4)

[0111] wherein k 1i is the permeability coefficient of the strong permeable layer (unit: m / d); M 1i is the thickness of the strong permeable layer outside the water stop curtain (unit: m); q i is the single well flow of the seepage well (unit: m 3 / d); L C is the contour perimeter of the basement (unit: m); R0is the influence radius of the seepage area (unit: m), .

[0112] The water head loss (unit: m) inside and outside the water stop curtain is calculated by the following formula:

[0113] (5)

[0114] wherein k i is the permeability coefficient of the weak permeable layer (relative aquifuge) (unit: m / d); M i is the thickness of the weak permeable layer (unit: m); D is the thickness of the water stop curtain (unit: m); d i is the thickness of the weak permeable layer at the bottom of the water stop curtain (unit: m).

[0115] For the inside seepage field, the water head loss (unit: m) along the path is calculated by the following formula:

[0116] (6)

[0117] wherein M 0iThickness of the highly permeable layer inside the stop curtain (unit: m); r is the distance between the seepage interception pumping well and the stop curtain (unit: m); r wi Radius of the seepage interception pumping well (unit: m).

[0118] Combining equations (4) to (6), the number n of seepage interception pumping wells arranged in the i-th precipitation unit. i Determine using the following formula:

[0119] (7)

[0120] in,

[0121]

[0122] The number of intercepting gravity flow wells is equal to the number of intercepting pumping wells.

[0123] (4) Anti-buoyancy safety calculation

[0124] By adjusting the seepage interception pumping well parameter n i r wi h wi q i The water level inside the waterstop curtain (unit: m) should be lower than the anti-buoyancy design water level (unit: m) if the following conditions are met:

[0125] (8)

[0126] in,

[0127]

[0128] In the formula, h cr Water level (unit: m) is set for anti-buoyancy design. i Let A be the self-weight and load weight of the superstructure within the i-th precipitation unit (unit: kN). i The structural base area of ​​the i-th precipitation unit (unit: m²) 2 ), γ w The specific weight of water (unit: kN / m³) 3 η is a safety factor greater than or equal to 1. Similarly, the arrangement of intercepting wells in each dewatering unit can be calculated and determined based on the distribution of the permeable layer thickness, the self-weight of the superstructure, and the load distribution.

[0129] Specifically, the layout of the cutoff wells transforms the basement from an irregular polygon into a rectangle with equal perimeters, and then from a rectangle into a circle. This conformal mapping transformation is calculated using the following steps:

[0130] (1) The conformal transformation process from rectangle to circle

[0131] like Figure 15As shown, the composite figure is obtained by 5 conformal transformations, which is the conformal mapping from the rectangle ABCD in z-plane to the circle in w-plane.

[0132] (2) Conformal mapping transformation calculation

[0133] Conformal mapping between z-plane and ζ' plane

[0134] (9)

[0135] where,

[0136] (10)

[0137] where F(θ,λ) is the first kind of incomplete elliptic integral, θ is its amplitude, λ(0<λ<1) is its modulus, and K(λ)=F(π / 2,λ) is the first kind of complete elliptic integral when θ=π / 2.

[0138] λ is determined by the aspect ratio a / b of the rectangle:

[0139] (11)

[0140] Conformal mapping between ζ' plane and t plane

[0141] (12)

[0142] Conformal mapping between t plane and ζ plane

[0143] Use exponential function or logarithmic function transformation:

[0144] (13)

[0145] Conformal mapping between ζ plane and w' plane

[0146] Use fractional linear transformation:

[0147] (14)

[0148] Conformal mapping between w' plane and w plane

[0149] Enlarge or reduce the unit circle in w' plane by a scale R to transform it into a circle with radius R in w plane:

[0150] (15)

[0151] Composite the above 5 transformations, and the conformal mapping function from rectangle to circle is obtained:

[0152] (16)

[0153] where γ is determined by the aspect ratio a / b of the rectangle:

[0154] (17)

[0155] where the first kind complete elliptic integral K(λ) with modulus λ is calculated by expansion:

[0156] (18)

[0157] (3) Coordinates of each plane are determined

[0158] Coordinates of point A on each plane:

[0159] z-plane: ;

[0160] ζ'-plane: ;

[0161] t-plane: ;

[0162] ζ-plane: ;

[0163] w'-plane: ;

[0164] w-plane: ;

[0165] Coordinates of point B on each plane:

[0166] z-plane: ;

[0167] ζ'-plane: ;

[0168] t-plane: ;

[0169] ζ-plane: ;

[0170] w'-plane: ;

[0171] w-plane: ;

[0172] Coordinates of point C on each plane:

[0173] z-plane: ;

[0174] ζ'-plane: ;

[0175] t-plane: ;

[0176] ζ-plane: ;

[0177] w' plane: ;

[0178] w-plane: ;

[0179] Regarding the coordinates of point D in each plane:

[0180] z-plane: ;

[0181] ζ' plane: ;

[0182] t-plane: ;

[0183] ζ-plane: ;

[0184] w' plane: ;

[0185] w-plane: ;

[0186] The angle between the line connecting corner points A, B, C, D and the center of the circle and the real axis. :

[0187] (19)

[0188] Combining equations (17) and (19), the included angle The relationship with the aspect ratio a / b of the rectangle is as follows: Figure 16 As shown, the larger the a / b value, the "flatter" the rectangle. The smaller the value, the better. When a / b = 1.0 (the rectangle is a square), we have... =π / 4; when a / b>4.0, <0.008 (0.46°).

[0189] In the above transformations, rectangle ABCD and unit circle ( Figure 15 The conformal mapping of (e) is unique. When the aspect ratio a / b of the rectangle is constant, the coordinates of the corner points A, B, C, and D on the unit circle are uniquely determined.

[0190] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A seepage interception well drainage system, characterized in that, include: A water-stop curtain (103) is set along the perimeter of the basement exterior wall (101), and cut-off wells, overflow drainage channels (102), water pumps (5), and drainage pipes (501) are arranged around the basement floor slab (1); the cut-off wells include cut-off pumping wells (2) and cut-off gravity flow wells (4), which are arranged alternately along the inner perimeter of the basement exterior wall (101); the cut-off pumping wells (2) and the cut-off gravity flow wells (4) are located in the underground permeable layer, and the depth of the cut-off pumping wells (2) is greater than the depth of the cut-off gravity flow wells (4); The overflow drainage channel (102) is located below the basement floor slab (1); the seepage interception pumping well (2) and the seepage interception gravity flow well (4) are connected through the overflow drainage channel (102), the seepage interception pumping well (2) passes through the overflow drainage channel (102) and the basement floor slab (1) in sequence, and the seepage interception gravity flow well (4) is located below the overflow drainage channel (102); The water pump (5) and part of the drainage pipe (501) are located inside the seepage interception pumping well (2). The drainage pipe (501) discharges the groundwater in the seepage interception pumping well (2) to the ground through the water pump (5). The seepage interception pumping well (2) and the seepage interception gravity flow well (4) are hamburger structures, which include an outer cylinder (201), an inner cylinder, a well shoe (203) and an isolation bottom plate (601). A first permeable filling material (205) is provided between the outer cylinder (201) and the inner cylinder. The well shoe (203) is located below the first permeable filling material (205), and the well shoe (203) is in contact with the side walls of the outer cylinder (201) and the inner cylinder. The isolation base plate (601) is used to close the bottom opening of the inner cylinder. A second permeable filling material (301) is provided below the isolation base plate (601). The second permeable filling material (301) is in contact with the well shoe (203). The cross-section of the well shoe (203) is an inverted triangular flared shape, and the bottom end of the well shoe (203) is an annular cutting edge shape.

2. The seepage interception well drainage system according to claim 1, characterized in that, The outer cylinder (201) is a plastic cylinder with a steel cage frame, and the inner cylinder is formed by binding steel wire mesh (209) with a steel cage (202); Multiple stiffening ribs (204) are provided between the outer cylinder (201) and the inner cylinder, and honeycomb-shaped water-permeable holes (207) are provided on the wall of the outer cylinder (201).

3. The seepage interception well drainage system according to claim 1, characterized in that, The overflow drainage channel (102) is configured as a rectangular overflow drainage channel (6) or a circular overflow drainage pipe (7).

4. The seepage interception well drainage system according to claim 1, characterized in that, The manhole cover (206) of the seepage interception pumping well (2) is flush with the top surface of the basement floor slab (1).

5. A method for preparing a seepage intercepting well drainage system as described in any one of claims 1-4, characterized in that, include: A closed water-stop curtain (103) is formed around the outer wall of the basement (101). The basement outline is divided into multiple dewatering units and the number of cutoff wells in each dewatering unit is determined; the cutoff wells include cutoff pumping wells (2) and cutoff gravity flow wells (4). The seepage interception wells and overflow drainage channels (102) are arranged around the basement floor slab (1); the seepage interception pumping wells (2) and the seepage interception gravity flow wells (4) are arranged alternately along the inner perimeter of the basement exterior wall (101); the seepage interception pumping wells (2) and the seepage interception gravity flow wells (4) are located in the underground permeable layer, and the depth of the seepage interception pumping wells (2) is greater than the depth of the seepage interception gravity flow wells (4); A water pump (5) and a drain pipe (501) are installed in the seepage interception pumping well, and the drain pipe (501) is connected to the ground drainage ditch. The overflow drainage channel (102) is located below the basement floor slab (1); the seepage interception pumping well (2) and the seepage interception gravity flow well (4) are connected through the overflow drainage channel (102), the seepage interception pumping well (2) passes through the overflow drainage channel (102) and the basement floor slab (1) in sequence, and the seepage interception gravity flow well (4) is located below the overflow drainage channel.

6. The method for preparing the seepage interception well drainage system according to claim 5, characterized in that, The basement outline is divided into multiple dewatering units, and the number of intercepting wells in each dewatering unit is determined, including: The shape of the basement outline is equivalent to a circle, and the radius R of the equivalent circle is obtained; the basement outline includes rectangles and irregular polygons; Based on the thickness distribution of the permeable layer in the basement and the self-weight and load distribution of the superstructure, several intersecting lines passing through the structural centroid of the basement are determined, dividing the basement outline into multiple dewatering units. Get the number n of seepage interception pumping wells arranged in the i-th precipitation unit. i Number of seepage interception pumping wells n i Obtained through the following formula: Where h0 is the initial water level of the site, L C L represents the perimeter of the basement. i Let k be the length of the inrush boundary of the i-th precipitation unit. 1i M is the permeability coefficient of a highly permeable layer. 0i and M 1i The thicknesses of the highly permeable layers at the bottom and outside of the basement are k, respectively. i and M i The permeability coefficient and thickness of the weakly permeable layer on the outside of the basement are q and q, respectively. i h is the flow rate of a single well in a seepage interception pumping well. wi ξ1, ξ2, and ξ3 are dimensionless resistance coefficients; The drag coefficients ξ1, ξ2, and ξ3 are obtained using the following formulas: Where R0 is the radius of influence of the seepage zone, D is the thickness of the stop curtain, and d i Let r be the thickness of the weakly permeable layer at the bottom of the stop curtain, and r be the distance between the seepage interception pumping well and the stop curtain. wi The radius of the seepage interception pumping well is given; the number of seepage interception pumping wells is equal to the number of seepage interception gravity flow wells.

7. The method for preparing the seepage interception well drainage system according to claim 6, characterized in that, The process of obtaining the radius R of the equivalent circle includes: If the shape of the basement outline is an irregular polygon, the irregular polygon is equivalent to a rectangle, and the rectangle is equivalent to a circle; if the shape of the basement outline is a rectangle, the rectangle is equivalent to a circle. When the outline of the basement is equivalent to a rectangle from an irregular polygon, the longer side 'a' and the shorter side 'b' of the rectangle are obtained using the formula... and Sure; When a rectangle is equivalent to a circle, the radius R of the equivalent circle is calculated using the following formula: in, Let a be the side length of the irregular polygon. max b is the maximum outer contour length of the irregular polygon. max This represents the maximum outer contour width of the irregular polygon.

8. The method for preparing the seepage interception well drainage system according to claim 6, characterized in that, The shape of the basement outline can be equivalent to a circle using the following method: Based on the shape of the basement outline, obtain the rectangle ABCD of the shape in the z-plane; An equivalent circle is obtained by using a conformal mapping function from a rectangle ABCD in the z-plane to a circle in the w-plane; wherein the conformal mapping function is: Where γ is determined by the aspect ratio a / b of the rectangle: In the formula, sn is the Jacobian elliptic function, K(λ) is the first complete elliptic integral, and λ is its modulus. In the above two formulas, λ is taken as 1 / γ. 2 or ζ is the intermediate auxiliary plane variable, i is the imaginary unit, and γ is the dimensionless physical quantity corresponding to the coordinates of the auxiliary point.

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