RU2013131615A - METHOD FOR DETERMINING THE LOADING ABILITY OF A BORING INJECTION PIL - Google Patents

Abstract

1. A method for determining the bearing capacity of a bored injection pile, comprising producing at least two bored injection piles according to the design technology adopted, characterized in that, in order to reduce the complexity and improve the accuracy of determining the bearing capacity, several cycles of borehole pressure testing are performed successively at a pressure of at least 4 kg / cm, lasting 10-12 minutes, after each cycle of pressure testing, cement-sand mortar is topped up to complete saturation of the well. 2. The method according to claim 1, characterized in that by measuring the total volume of the poured mortar for all pressure testing cycles, the radius of the injection pile is determined by the formula (I): where R is the radius of the pile, m; R is the radius of the well, m; L is the depth of the well, m; V is the total volume of the poured solution, m; P is the pressure of the test m. water station; E is the soil deformation modulus, tf / m; μ is the coefficient of lateral expansion of the well at the pressure (P) of the test: where φ is the angle of internal friction soil 25-40 °; ε - coefficient of porosity; α - coefficient of pore filling with cement-sand mortar; accordingly, I bear taking into account the expansion of the walls of the well is determined by the formula (2): where F is the bearing capacity of the pile, tf; R is the estimated soil resistance under the lower end of the pile, tf / m, according to tables SNiP 2.02.03-85 or SP50- 102-2003 “Design and construction of pile foundations”; A is the area of support of the pile, taken equal to the cross-sectional area of the injection pile, is located through the radius R, m; u is the perimeter of the pile shaft, determined by the radius R of the pile, m; γ is the coefficient of the conditions of operation of the pile in soil, taken equal to γ = 1, independently about soil type; γ- conditions coefficient

Claims (2)

1. A method for determining the bearing capacity of a bored injection pile, comprising producing, according to the design technology adopted, at least two bored injection piles, characterized in that, in order to reduce the complexity and improve the accuracy of determining the bearing capacity, several cycles of well testing under pressure of at least 4 kg / cm ² , lasting 10-12 minutes, after each cycle of pressure testing, cement-sand mortar is topped up to complete saturation of the well. 2. The method according to claim 1, characterized in that by measuring the total volume of the poured mortar for all pressure testing cycles, the radius of the injection pile is determined by the formula (I): $$R_{\mathrm{from}\mathrm{at}}=\sqrt{\frac{\mathrm{one}+\epsilon }{\epsilon \alpha }\left\{\left(\frac{V_{d\mathrm{about}l}}{\pi L}+R_{\mathrm{from}\mathrm{to}\mathrm{at}}^2\right)-{\left[R_{\mathrm{from}\mathrm{to}\mathrm{at}}\left(\mathrm{one}+\frac{\left(\mathrm{one}+\mu \right)P}{E}\right)\right]}^2\right\}+{\left[R_{\mathrm{from}\mathrm{to}\mathrm{at}}\left(\mathrm{one}+\frac{\left(\mathrm{one}+\mu \right)P}{E}\right)\right]}^2};\left(\mathrm{one}\right)$$

where R _St is the radius of the pile, m; R _SLE - well radius, m; L - well depth, m; V _dol - the total volume of the poured solution, m ³ ; P is the pressure of the test m. Water; E - soil deformation modulus, tf / m ² ; µ is the coefficient of transverse expansion of the well at a pressure (P) of pressure testing: where φ is the angle of internal friction of the soil 25-40 °; ε is the porosity coefficient; α is the coefficient of pore filling with cement-sand mortar; accordingly, the bearing capacity of the injection pile, taking into account the expansion of the walls of the well, is determined by the formula (2): $${\text{F}}_{\text{d}}={\text{γ}}_{\text{c}}\left({\text{γ}}_{\text{cR}}\text{R}{\text{A}}_{\text{R}}+{\text{u}}_{\text{R}}{\displaystyle \sum {\text{γ}}_{\text{cf}}{\text{f}}_{\text{i}}{\text{h}}_{\text{i}}}\right)\text{;}\left(\text{2}\right)$$

where F _d - bearing capacity of piles, hardware; R is the calculated soil resistance under the lower end of the pile, tf / m ² , according to the tables SNiP 2.02.03-85 or SP50-102-2003 "Design and construction of pile foundations"; A _R is the bearing area of the pile, taken equal to the cross-sectional area of the injection pile, is located through the radius R _s , m ² ; u _R - pile shaft perimeter, defined by the radius R of the pile _binding, m; γ _s is the coefficient of pile working conditions in the soil, taken equal to γ _s = 1, regardless of the type of soil; γ _cR — coefficient of the working conditions of the pile under the lower end of the pile, taken equal to γ _s = 0.8, regardless of the type of soil; γ _cf — coefficient of working conditions of the i-th soil layer on the lateral surface, taken equal to γ _cf = 0.9, regardless of the type of soil; f _i is the calculated resistance of the i-th soil layer on the lateral surface of the trunk, taken according to the tables SNiP 2.02.03-85 or SP50-102-2003 “Design and construction of pile foundations”; h _i is the thickness of the i-th soil layer in contact with the side surface of the pile, m