On the formation of a waterproofing shell around the underground structure lining in watered ground

Andrey Uglyanitsa

doi:10.1051/e3sconf/202131502005

Abstract

To prevent the filtration of groundwater into the used underground structure in operation through its lining, it is proposed to make two waterproofing shells by the underground method around the outer surface of the lining of an underground structure; the upper one is made of the soil mass compacted by cementation with reduced water permeability and the lower one is made of the silicate cement. To make the upper shell, boreholes are drilled from an underground structure through its lining and the cement mortar is alternately injected through them into the watered ground providing its hydraulic fracturing; and to make the lower shell, injection pipes with a diameter of 102-152 mm are installed between the boreholes in the lining flush with its outer surface, the silicate cement mortar is alternately injected into the injection pipes, an incipient crack is created between the outer surface of the lining and the ground under the action of the mortar injection pressure on the ground opposite the injection pipe, an incipient crack is hydraulically extended along the contact of the lining with the ground and filled with the silicate cement mortar until refusal to absorb it. To determine the optimal parameters of the hydraulic separation process, tests were carried out on the laboratory table simulator.

Highlights

During the use of underground structures located in watered grounds, over time, physical wear of the underground structure lining occurs and the continuity of its waterproofing coating is disturbed
The purpose of the experiments was to find the rational composition of the silicate cement mortar, the injection of which with the given final pressure value would make it possible to form the thickest silicate cement layer δ in the hydraulic separation crack
The performed experimental studies have shown that for the formation of a waterproofing shell made of the silicate cement around the lining of an underground structure, the most rational composition of the silicate cement mortar is a composition with a ratio C:W=1:0.75 with the addition of sodium silicate in an amount of 5% by weight of the cement

Summary

Introduction

During the use of underground structures located in watered grounds, over time, physical wear of the underground structure lining occurs and the continuity of its waterproofing coating is disturbed. Groundwater, filtering through a worn-out waterproofing coating and lining, penetrates into the underground structure, impedes its normal use and has a corrosive effect on the underground structure and the equipment located in it. In unstable watered grounds, the soil mass to be excavated is preliminarily supported with a "pile planking" or "diaphragm wall" and, if necessary, the walled soil mass is unwatered [2, 3, 4] The disadvantage of this technology for replacing the waterproofing shell of an underground structure is the high cost and labor-intensity of the excavation and backfilling, walling and dewatering of the soil mass, which grow with an increase in the depth of an underground structure. After fracturing the ground with the cement mortar, the soil is compressed by expanding hydraulic fracturing cracks due to the supply of the cement mortar, increasing the density and strength of the ground and, as a result, its water resistance within the length of the wells

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Conclusion