SU1351997A1 - Method of compacting the body of sagging loess soil - Google Patents

Abstract

The invention relates to the construction, in particular to the compaction of an array of loess subsided soil by a hydraulic blasting method. The purpose of the invention is to reduce the duration of the zero construction cycle by compensating for uneven soil deformations in the period of post-explosion consolidation. This is achieved by soaking the array, leaving the upper non-wetted layer and the construction of a compacted dirt cushion in the pit. The thickness of the soil cushion is determined by the proposed calculated dependence. Reduction of water consumption for soaking and increase of operational reliability of erected structures is provided. 2 Il. with joint venture with

Description

The invention relates to the construction, in particular to the compaction of an array of loess subsided soil, mainly at the base of buildings and structures during their construction, in a hydraulic blasting manner.

The purpose of the invention is to reduce the duration of the zero cycle of construction by compensating for uneven deformations of the soil during the period of nosklivryvaya consolidation.

FIG. Figure 1 shows a section of the pilot array during the soaking period; in fig. 2 - the same, after the erection of the dirt pad.

The method is carried out as follows.

Within the compacted area, the vegetation layer 1 is cut, the drainage and blast holes 2 are drilled, pipes 3 are installed in them, the annulus is filled with drainage material 4 to the upper boundary of the soaking zone 5, and in the upper non-spud zone 6 - waterproof material 7 For example, clay or cement mortar. After this, the subsidence of the soil in the zone 5 is soaked by supplying water through the pipes 3. With conditional stabilization of the subsidence, the soaking is stopped, the bottom of the pipe 3 is sealed, for example, filled with cement mortar, then explosives 8 are placed in the pipes 3 in the soaked zone 5 and t explosions. The presence of an unsoaked zone 6 in the upper layers of the compacted base creates a seismic shield, which makes it possible to use the action of the explosion in the wetted soil more purposefully, to more completely destroy the structural connections of the weakened by soaking subsiding soil.

After the subsidence, zone 6 is partially removed, the pipes 3 are removed and the remaining part of the under-compacted layer is compacted with 9 heavy-duty tampers.

In order to eliminate uneven deformations of the soil during the stabilization period, the sediment after the explosion, a compensated over-compacted soil underlay 10 is placed on the compacted soil layer of the buffer zone 9. The feed bed 10 is laid in layers and compacted at optimum humidity with tampers or rollers given degree of soil compaction. The degree of over-compaction of the separated layer is determined by the ratio

. -,

- jil

rkrp

where RP, rcrm is the density of dry and medium over the layer is the critical density of the soil

PODPU 1KI, G / CM.

With .Mf, the soil is in the normally compacted state, and with

 - in the repacked and underpacked states, respectively.

The mechanism of compensation of uneven deformations in the pillow operates as follows. In case of uneven deformations of the soaked underlying soil 5, the over-compacted support 10 undergoes unloading from below, which causes expansion or compressive horizontal and vertical stresses in it. Under the action of these stresses, the soil particles are displaced relative to each other, which causes the over compacted soil feeder 10 to loosen up, and the effect of dilatancy of the soil is manifested. The loosening of the soil cushion compensates for uneven deformations caused by subsidence.

The design density of the feeder pp is determined from the condition that the bottom of the feeder, when fully water-saturated, is in the normally-compacted state, i.e., the value of pp must correspond to the critical density of the soil pcr determined under the condition of full water saturation and pressure at the base of the foundation. on the ground cushions. After laying each layer, the moisture content of the soil of the spreader is reduced to 5. 0,, 3 by drying. In such a state, the soil liner will have the maximum compensation ability, i.e., the ability to loosen significantly when deformed and to repay uneven drawdowns.

The thickness of the compensated re-compacted soil sheet is determined from the dependence

Yap 1 () K, (i - gvr

where A is the coefficient characterizing the degree of compensation for permissible unequal-dimensional deformations; K - coefficient taking into account the degree of disturbance of the soil structure pn, p ° np - density of dry

and oboben.1enna critical density of the soil of the sheet; 5.10П - permissible non-uniform deformations; T is the time of conditional stabilization of the sediment; Q - coefficient of proportionality of increments of non-uniform

sediment during stabilization of soil deformations after the explosion.

The value of the coefficient A varies from 0 to. With the compensatory properties of over compacted soils are not taken into account; at And 1 uneven

the deformations of the lower weak ground are fully compensated by the bushing; when partial compensation of deformations is observed, and the remaining part of irregular sediments is perceived by the building structures. The value of L is advisable to assign

according to the results of the feasibility study.

The coefficient of disturbance of the soil structure Kp will be determined in situ or laboratory conditions. It varies in range from O to 1. When Kp. 0 the structure of the nodushka is not disturbed, with, Kp 1 there is a partial or complete disruption of the structure of the soil, repacking of its particles,

0.15-C, 30 0.20-0.33 0.25-0.35 0.2-0.35 0.1-0,:

loosening the pillow and compensating for uneven drawdowns. In case of uneven deformation of the soil caused by subsidence of the underlying soil. Ki is within the limits shown in the table.

0.05-0.2

The compensating ability of the over compacted cushion soil is quite high in a low moisture soil at 0-0.45. Therefore, in order to protect the soil from moisture on the slopes of the pit and the underlying soil cushion, if necessary, install water protection screens.,.

The application of the proposed method reduces the water consumption for soil soaking, reduces the time required for the preparation of bases, compensates for uneven deformations, increasing the operational reliability of the structures being built.

Claims (1)

Invention Formula A method of compacting an array of loess shrinkable soil is predominantly at the base of buildings and structures, including the formation of wells, soaking the soil mass through them, placing them in wells and blasting explosive charges, fragment of the excavation, compacting the soil layer in it and erecting an earth cushion , characterized in that, with / 1 8 4 five in order to reduce the duration of the zero construction cycle by compensating for uneven deformations of the soil in the period of post-explosive consistency, the soaking of the soil mass is conducted from the foot of the layer to be compacted by tamping down the layer to a predetermined depth, and erecting the subsoil 1 pillows are determined from dependencies   PT-5L "--A) where is np 0 five Kni sse I Jftpn soil cushion thickness, m; sediment increment coefficient after explosions, m; duration of conditional stabilization of sediment, days; Layer 5 — permissible uneven deformations for buildings and structures, m; - coefficient of compensation for uneven deformations; - coefficient of the degree of violation of the pillow's soil structure; -the density of dry and generalized critical density of the soil according to DUP1KI. T - BUT KP OY rcr water. FI.2