SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a composite sandwich liner barrier type impervious wall with good dry cracking resistance, good shear strength and good seepage resistance.
The composite sandwich liner barrier type impervious wall comprises 2 natural impervious material layers and a geomembrane layer, wherein the 2 natural impervious material layers and the geomembrane layer are laid along a seepage side slope, the geomembrane layer is clamped in the 2 natural impervious material layers, and an anchoring ditch is formed in the platform position of the side slope and used for fixing the geomembrane.
Preferably, the composite sandwich liner barrier type impervious wall further comprises a buffer barrier arranged at the bottom of the side slope.
The natural impermeable material layer is a clay layer or a bentonite layer, and is preferably a clay layer; the geomembrane layer is an HDPE film layer, and preferably has two rough surfaces with the thickness of 2 mm.
The buffer barrier is a pollution-free benign waste stone layer, and the thickness of the buffer barrier is more than or equal to 5 m.
The geomembrane is fixed in an anchoring mode or a ballasting mode in the anchoring ditch.
In the geomembrane construction process, the lap joint between the geomembranes adopts double-track welding, and the connecting part between the geomembranes needs to be controlled at the position of the anchoring ditch, so that transverse welding seams do not appear on the side slope as much as possible.
The water content of the natural impermeable material is controlled to be 16.5-22.0%, and the total thickness of the 2 layers of natural impermeable material layers is more than or equal to 10 m.
The utility model has the beneficial effects that: the utility model equally divides the natural anti-seepage material into two parts according to the thickness for construction, the two parts are divided into a lower half part and an upper half part, the artificial anti-seepage material is evenly paved on the natural anti-seepage material after the lower half part is constructed, then the upper half part of the natural anti-seepage material is constructed, and the artificial material is constructed into the natural material in a sandwich mode to form the composite sandwich lining barrier which achieves the anti-seepage effect. The two materials are combined together, and the artificial material is embedded into a natural material as a sandwich, so that the method can overcome the risk that the permeability coefficient is smaller and the service life is longer, and can solve the problems of poor anti-cracking performance and poor shear strength capability.
Detailed Description
Example 1
Taking a certain slope seepage-proofing project as an example, the structure schematic diagram of the seepage-proofing wall is shown in fig. 1, and the specific construction process is as follows:
the method comprises the following steps: designing the impervious wall: the design slope ratio of the impervious wall is less than or equal to 1:2, the horizontal total thickness of the natural impervious material layer 4 on the upper half part and the natural impervious material layer on the lower half part is more than or equal to 10m, the natural impervious material layer adopts clay as a material, and the geomembrane adopts a high-density polyethylene geomembrane (HDPE) with 2mm thick double rough surfaces. The construction process of the impervious wall comprises the following steps: the method comprises the following steps: constructing a buffer barrier 6+ the lower half part of the natural impermeable material layer 2, laying and welding the geomembrane layer 3, and constructing the upper half part of the natural impermeable material layer 4.
Step two: construction of buffer barrier 6+ lower half part natural impermeable material layer 2
(1) The filling construction preparation comprises the steps of firstly, completely cleaning loose blocks of andesite rocks (bottom boundaries of the impervious walls) on the side slopes by using a hydraulic stone breaking machine before filling the impervious walls, cleaning the loose blocks by using a high-pressure water gun without other sundries such as broken stones, slurry and the like, carrying out combined concealed engineering acceptance after cleaning, and filling clay wall materials after acceptance.
(2) And (3) measurement and paying-off: because the slope ratio of the lower impervious wall is 1:2, the initial elevation is low in the north and the south, and the slope change of the east side slope of the S pit is large under the current situation, the bottom edge boundary line of each filling area needs to be measured and determined according to the design requirements in different areas, the bottom edge boundary line is marked by using piles or lime spraying lines, and the impervious wall is filled according to the designed slope ratio by paying off every 2m in the wall filling process.
(3) Filling of the buffer barrier: at the bottom of the impervious wall, a layer of non-pollution benign waste rock (NAF) with the thickness of 5m is filled firstly to be used as a first buffer barrier 5 between the acidic waste rock and the impervious wall body. The layer is compacted in a backfill process, and the layering thickness is 0.5-1 m.
(4) And (3) constructing the lower half part of the natural impermeable material layer 2:
4.1 soil body spreading: clay materials are paved along the slope trend of the impervious wall, the once paving thickness is controlled to be 30cm, soil materials are paved and leveled by a bulldozer and a loader, and the paving thickness is measured at any time, so that the uniformity of thick soil materials is ensured;
4.2 soil moisture content control: according to the results of the indoor geotechnical tests, the optimal water content is controlled to be 16.5-17.8%. The water amount of sprinkling is according to the design standard and the rolling test result, the climatic conditions of Burma high temperature are considered, and the actual soil requires that the water content is higher than the optimal water content (+ 1% -3%). According to the rolling test data and the characteristics of the engineering terrain, water in the slope intercepting ditch is utilized, and two sets of water spraying pipelines are adopted to properly add water to the incoming soil on the working face.
4.3 rolling the soil body: the rolling is carried out along the axial direction of the wall body by adopting a 15t bump vibration rolling mode, wherein the rolling mode is a forward-backward offset method, and the offset width is 0.27 cm. Preliminarily determining that rolling is carried out for 8 times, alternately carrying out static pressure and vibration, carrying out static pressure for 4 times and vibrating for 4 times, determining the actual rolling times according to a field compaction test, and controlling the rolling walking speed to be 2.5 km/h. Tamping the corner parts by a frog rammer. The soil body compactness is not less than 95%.
4.4 on-site detection in the soil compaction process, every time in the soil compaction process of the wall bodyThe soil material of 3 ten thousand squares is subjected to a group of clay undisturbed sample soil working tests, and the particle size distribution, the natural water content, the plastic limit and the liquid limit of the soil body, the optimal water content and the maximum dry density of the soil body are measured. Each layer is 50m2And one group of cutting ring samples are adopted on site, and the compactness and the dry density are detected on site. Soil samples should be collected for further testing; the wall body is filled by adopting sectional flow line production, and the wall body rises uniformly;
4.5 repeating the steps 4.1-4.4 until the thickness of the clay layer reaches 5m, and obtaining a clay layer which is the lower half part of the natural impermeable material layer 2.
Step three: laying and welding geomembrane
(1) And the lower half part of the natural impermeable material layer 2 is compacted to be qualified, after slope repairing, the lower half part of the natural impermeable material layer reports to the supervision and the acceptance of an owner, sharp sundries such as broken stones, rubbles, root hairs, reinforced concrete particles or glass fragments and the like can not appear on the inner side compacted clay slope surface contacted with the geomembrane, and after the acceptance is qualified, the HDPE impermeable film is laid.
(2) The type, specification and quality of the HDPE impermeable membrane are subjected to standardized inspection before construction, the inspection and acceptance of the impermeable membrane are strictly in accordance with relevant standard standards, and the impermeable membrane is accepted and used after being qualified.
(3) Laying an HDPE impermeable film: after the roll-pressing slope repairing of the inner side impervious wall is finished (one subsection is 5-6 m high), the geomembrane is laid along the axial direction of the impervious wall, smooth and solid laying is carried out, wrinkles are reduced as much as possible, and the geomembrane is timely ballasted or anchored after the laying. When the construction is carried out on a side slope, the soft climbing ladder is adopted to ascend and descend.
(4) The fixing of the earth work die (HDPE) is realized through an anchoring ditch, every 5m (vertical height) utilizes a 5m wide soil platform filled on the inner side of the side slope as an anchoring platform, the size of the anchoring ditch is 1m (width) multiplied by 1m (depth), the reserved amount of the seepage-proofing material is anchored in the anchoring ditch, and the seepage-proofing material is turned out after the construction of the next stage and is connected with the seepage-proofing material of the next stage. Meanwhile, the part of the anchoring ditch is used as the position of the upper roll and the lower roll of the geomembrane for transverse welding joints.
(5) The geomembrane welding is from bottom to top, and transverse welding seams do not appear on the side slope as much as possible. Two connected rolls of transverse joints are arranged in the anchoring ditch as much as possible, and adjacent seams are staggered by more than 1 m.
(6) The overlapping of the HDPE anti-seepage films is welded by adopting a hot melting double rail of an HDPE anti-seepage film automatic welding machine, the welding width is 10cm, and the allowable error is 2 cm. The welding should be carried out at 40 ℃ avoiding the high noon time in the mine.
(7) The welding rod material used for connecting the HDPE anti-seepage film and the HDPE anti-seepage film are made of the same material and are produced by the same material in the same factory, and substitute welding rods cannot be adopted.
(10) And (3) air tightness detection: and the air tightness is detected by an air pressure detector. And (3) forming a double-track welding line by hot melting welding, reserving an air cavity in the middle of the welding line, plugging two ends of the welding line air cavity after one welding line is constructed, pressurizing the welding line air cavity to 250kPa by using a pressure detector, maintaining for 3-5 min, wherein the air pressure is not lower than 240kPa, then opening a hole at the other end of the welding line to deflate, and rapidly returning to zero to be qualified by using an air pressure gauge pointer. The needle hole left by the air pressure detection must be sealed by welding.
Step four, constructing the upper half natural impervious material layer 4
4.1 soil body spreading: clay materials are paved on the geomembrane along the slope direction of the impervious wall, the thickness of the paving materials at one time is controlled to be 30cm, soil materials are paved and leveled by a bulldozer and a loader, and the thickness of the paving materials is measured at any time, so that the uniformity of thick soil materials is ensured;
4.2 soil moisture content control: according to the results of the indoor geotechnical tests, the optimal water content is controlled to be 16.5-17.8%. The water amount of sprinkling is according to the design standard and the rolling test result, the climatic conditions of Burma high temperature are considered, and the actual soil requires that the water content is higher than the optimal water content (+ 1% -3%). According to the rolling test data and the characteristics of the engineering terrain, water in the slope intercepting ditch is utilized, and two sets of water spraying pipelines are adopted to properly add water to the incoming soil on the working face.
4.3 rolling the soil body: the rolling is carried out along the axial direction of the wall body by adopting a 15t bump vibration rolling mode, wherein the rolling mode is a forward-backward offset method, and the offset width is 0.27 cm. Preliminarily determining that rolling is carried out for 8 times, alternately carrying out static pressure and vibration, carrying out static pressure for 4 times and vibrating for 4 times, determining the actual rolling times according to a field compaction test, and controlling the rolling walking speed to be 2.5 km/h. Tamping the corner parts by a frog rammer. The soil body compactness is not less than 95%.
4.4 field detection in the soil body rolling process, in the wall body soil compaction process, performing a group of clay undisturbed sample soil working tests every 3 ten thousand square of soil materials, and determining the particle size distribution, the natural water content, the plastic limit and the liquid limit of the soil body, the optimal water content and the maximum dry density of the soil body. Each layer is 50m2And one group of cutting ring samples are adopted on site, and the compactness and the dry density are detected on site. Soil samples should be collected for further testing; the wall body is filled by adopting sectional flow line production, and the wall body rises uniformly;
4.5 repeating the steps 4.1-4.4 until the thickness of the clay layer reaches 5m, and obtaining a clay layer which is the lower half part of the natural impermeable material layer 4.
The structure of the diaphragm wall obtained after construction is shown in figure 1, a layer of waste rock buffer barrier 5 with the thickness of 5m is filled at the bottom boundary of a seepage side slope 1, a layer of lower half part natural seepage-proof material layer 2 is rolled and filled along the slope of the seepage side slope 1, a layer of geomembrane layer 3 is laid on the lower half part natural seepage-proof material layer 2, and the geomembrane layer 3 is fixed on the side slope in a ballasting or anchoring mode through an anchoring ditch 6; the anchoring ditch 6 is arranged at the platform position of the seepage side slope 1; the geomembrane layer 3 is filled with an upper half part of a natural impermeable material layer 4 in a rolling way.
Through tests, compared with the common construction method, the impervious wall structure in the embodiment can save impervious materials, has good impervious effect, and the saturated impervious coefficient of the impervious wall is less than 1 multiplied by 10-9cm/s, long service life of the impervious wall, and 100 years of endurance life.