Operation of pipe water transmission structure in interaction with subsiding soil

2. Methods
Typical epyura of jet attempts of loess soil to pressure of a diaphragm of tubular moving – difference, obtained during pilot investigations. The epyura corresponding to a diaphragm's lag on a pipe, as well as the duration of partial moistening of a diaphragm's foundation, are of particular interest for future investigation. In many instances, the practical epyura of loess soil jet attempts differs greatly from the predicted epyura.
The diaphragm is assumed to be a monolithic construction. This is the case if the seams joining the separate diaphragm plates are strong enough. The "freezing" of the diaphragm on the pipe necessitates the most effort at these seams. In this scenario, the force felt by one joint will be equivalent to:


N _s = Q₁ -P_а b l₁ (1)

where Q₁ is the weight of the diaphragm's extreme plate, kN; P_аis the average contact pressure between the extreme plate and the base; b denotes the breadth of the diaphragm plates in centimeters;l₁is the length in centimeters of the longitudinal edge of the base of the diaphragm's extreme plate;

It can be assumed equal to the initial subsiding P_а= P_in , kN/sm² in the event of soaking the soil under the whole diaphragm; the friction force between the plates and the ground is very modest and goes to the safety margin in formula (1) is not taken into consideration.
The necessary cutting area of the diaphragm plate weld will thus be equal to:
sm²
where Rs is the estimated shear material cut resistance in kN/sm^2.

3. Results and Discussion
The diaphragm can be approximated as a beam with a large h/b ratio according to the scheme illustrated in Fig. 1 and matching to the aperture period of the diaphragm if the integrity of the joints connecting the cap plates is assured.