When a rock mass with a structural plane is destroyed along the weak plane, the shear stress acting on the plane ([[tau].sub.n]) should exceed its ultimate shear stress ([[tau].sub.f]) caused by the normal stress.
where [[tau].sub.f] is the ultimate shear stress caused by the normal stress, MPa.
For the free head pile in dense sand, the ultimate shear stress
mobilized at z = 18 m was 505.8 kPa, which is close to that in the reference case without thermal cycles (522.2 kPa).
where [[tau].sub.s.u.i]--an ultimate shear stress; K--a coefficient of lateral earth pressure; [[sigma]'.sub.vo]--vertical effective stress in the soil; [[delta].sub.s]--a coefficient of interface friction.
At F1 area ultimate shear stress mobilized when settlement was 10 mm, and at F2 area the ultimate shear stress mobilization did not appear at all (Fig.
At F2 area the significant higher ultimate shear stress mobilized when settlement has reached 10 mm.
With the use of concrete with a cube compressive strength [f.sub.cu] = 60 MPa, the transverse reinforcement ratio ([[rho].sub.sv]) was first set to give a theoretical ultimate shear stress in the RC component ([[nu].sup.*.sub.rc]) of about 6 MPa, which was close to the maximum allowable value of 6.2 MPa given by the new code of practice in Hong Kong .
They were all provided with a plate anchorage length of 500 mm ([L.sub.a]/l = 0.5) and designed with roughly the same theoretical ultimate shear stress ([[nu].sup.*.sub.u] [approximately equal to] 12 MPa) but different ultimate strengths.
As a result, the calculated ultimate shear stress
differs significantly from the published overlap shear strength of the adhesive provided in Table 1.
where [[tau].sub.lim] is ultimate shear stress
, [mu] is the sliding friction coefficient, and it equals 0.5 in this paper, P is the contact compressive stress in normal direction, b is the cohesion between the adjacent layer, and [tau] is the equivalent shear stress.
[[tau].sup.*] is the ultimate shear stress
for a unit volume of material, at a given probability of failure, calculated from the finite element stress distribution from the relationship: