Water-rich stratum foundation pit sheet-pile wall inter-pile gravel inverted filtration anti-seepage structure and construction method

The invention belongs to the field of foundation pit supporting, and particularly relates to a water-rich stratum foundation pit sheet-pile wall inter-pile gravel inverted filtration anti-seepage structure and a construction method. The water-rich stratum foundation pit sheet-pile wall inler-pile gravel inverted filtration anti-seepage structure comprises front-row cast-in-place piles and rear-row cast-in-place piles which are arranged in two rear rows, a pile front soil retaining plate is arranged on the front sides of the front-row cast-in-place piles, the space between the rear side of the pile front soil retaining plate and the front-row cast-in-place piles is filled with a sand gravel inverted filter layer, clay I is arranged at the bottom of the sand gravel inverted filter layer I, and a plurality of drainage holes I are formed in the pile front soil retaining plate and communicate with the sand gravel inverted filter layer I and the outside; a top beam is arranged between the tops of the front-row cast