SU1643661A1 - Method and apparatus for determining stressed state of a soil body - Google Patents

Abstract

The invention relates to the construction, in particular to the study of the stress state of soils in an array of field methods. The aim of the invention is to increase and simplify measurements by reducing the amount of research on Hollow cylinder 1 crushed into the soil from the free surface or from the bottom of the well. At the same time, the volume of soil 7 separated from the massif falls inside the hollow cylinder 1, where, due to the increase in the diameter of the upper section 4 of the hollow cylinder 1 and the ability of the soil to move freely, the stresses in it fall to zero. By means of sensor 6, this voltage drop is measured by registration of the change in the flux of infrared radiation of the soil, proportional to the voltage drop in a separated volume of soil; The voltage acting in the soil mass is estimated from the value of the flux of infrared radiation recorded by the sensor com 6 IR radiation at the moment of crushing the hollow cylinder 1c in the soil and is calculated according to the formulas 2CoPof-ly, 4 silt S8

Description

The invention relates to the construction, in particular to the study of the stress state of soils in an array of field methods.

The purpose of the invention is to increase the accuracy and simplify measurements by reducing the amount of research,

Fig o1 shows a device for implementing the method, a general view; Fig 2 is the same at the moment of pressing into the ground; Fig. 3 is a calibration circuit for an infrared (IR) radiation sensor; 4 is a graph of IR flux versus load;

The device contains a hollow cylinder 1, which has a conical sharpening of the outer surface 2, and the internal cavity - two sections 3 and 4 of different diameters, separated by an annular access 5 o The section 3 with a smaller diameter is located on the side of the conical sharpening 2. The length of section 3 is assigned according to with ratio:

h, 06 D, mm, where h is the length of the section with a smaller diameter, mm;

D - diameter of the cavity section on the sharpening side, mm „

The device also contains a sensor

thirty

6 to determine the stress state of the soil, made in the form of an infrared radiation receiver and installed on the free surface of the detachable array 7 inside the hollow 35 Cylinder 1 with the possibility of moving Csh along its axis0. Wires from it are led out through the hole in the cylinder 1 o

The method is implemented as follows: 40

ZOM0

A stamp 8 with a germanium window 9 and an infrared radiation sensor 6 is installed on the free surface of the soil 7, for example, at the bottom of a well. Using a 45 crushing device (not shown), a known pressure is created on the stamp, registering the corresponding flow change IR radiation "But the data obtained is used to build a calibration dependence (Fig04) 0

The hollow cylinder 1 is crushed into the ground with the help of a jack (not shown) from the free surface or from the bottom of the well. At the same time, the volume of soil 7 separated from the array 55 enters into the interior of the hollow cylinder 1, where due to the increase in the diameter of the upper section 4

Q j

0

five

0

five

0

45 0

five

hollow cylinder 1 and the ability of the soil to move freely, the voltage in it drops to zero 0 With the help of sensor 6, this voltage drop is measured by recording the change in the amount of infrared radiation flux from the soil proportional to the voltage drop in the separated volume of soil.

The area of the central part of the end surface of the detachable volume, on which infrared radiation is recorded (the area under the sensor), is designated within 0.05-0.25 of the area of the end surface of the detachable array a

The voltage acting in the soil mass is estimated by the value of the IR radiation flux recorded by the IR radiation sensor 6 at the moment of the crushing of the hollow cylinder 1 into the soil 7 and is calculated by the formulas:

„WB

 - with vertical crushing flat cylinder;

g w

U + b 7 with horizontal crushing,

where GT is the vertical component

stress tensor, MPa; Ug is the horizontal component of the stress tensor, MPa;

Wf, Wg - flux density of infrared radiation, respectively, with horizontal and vertical pushing,

Uw

BUT -. - calibration factor L.P.

thermoelasticity

UW - change in flux density

IR radiation, W / m 2; change in voltage acting on the ground when adjusting

The positive effect from the use of the invention is to reduce the measurement error of the actual stresses acting in the soil mass

The method and device are suitable for determining the magnitude of stresses acting in an array of several soils (with the exception of silty-clay soils of solid consistency) and Soils that have frequent inclusions of large fractions of rubble, rock pebbles, and water-saturated soils.

Claims (1)

Invention Formula 1 o A method for determining the stress state of an array of soil, including the formation of a cavity in it, loading, measuring the parameters of the soil condition and determining stresses, characterized in that, in order to improve accuracy and simplify measurements, a load is first applied to the array soil with a stamp measuring the infrared radiation of the soil and determine the dependence of the magnitude of this radiation on the load, and the formation of a cavity in the soil mass is made by inserting a hollow cylinder into it The inside of the cylinder contains a limited amount of soil with a free end surface, in which the infrared radiation of the soil is measured by installing a sensor on the central part of the end surface of a limited amount of soil, while the ratio of its area to the area of the entire end surface is 0.05-0. 25, after which the voltage of the soil array is determined from the value of the measured infrared radiation using a pre-determined dependence on the load; 20. An apparatus for determining the stress state of an array of soil, comprising a housing with a sensor, characterized in that the housing is made in the form of a hollow cylinder with a conical sharpening of the outer surface at one end, and the cavity has two sections of different diameters separated by a flat annular ledge the section with the smaller diameter is located on the side of the conic sharpening of the external surface, and the length of this section is assigned in accordance with the ratio h 0.02-0.060, mm, where h is the length of the section with the smaller diameter, mm, D is the diameter section of the cavity on the sharpening side, mm, while the sensor is made in the form of an infrared radiation receiver and is placed inside the housing with the possibility of movement along the central axis of the latter. Fi & 1 Sh 0, Z " 0.20 / 0.6Ot & ultfltta FIG. four. Fig.Z / /