The effect on residential life for the tunnel construction
With the appearance of tunnels in the city or downtown, residential life and building is influenced inevitably by drilling and blasting construction at the entrance of tunnel. In order to reduce the effect, the monitoring of effect on resident, such as dust and noise was conducted during the construction of the entrance of tunnel. The monitoring result shows: (1) Dust content is 20 mg/m3 at the entrance of tunnel for blasting. It is 60 mg/m3 during the construction of wet pneumatically placed concrete. It is higher than the standard of health, 5.3 mg/m3. (2) Noise is 85 decibels when ventilation and noise is 200 decibels during the construction of drilling that is more than the standard, 60 decibels. It provides the reference for similar engineering.(3)The surface settlement induced by drilling and blasting in tunnels affects residential life.
Micromechanical modelling of the mechanical properties of a granite under dynamic uniaxial compressive loads
A micromechanics-based model is used to study the mechanical properties of a granite under dynamic uniaxial compressive loads. The model is based on interacting sliding cracks uniformly distributed in the rock material. A dynamic crack growth criterion, which is related to crack growth velocity and dynamic fracture toughness of the rock material, is employed in the analysis. Under dynamic loads at strain rates from 10−4 to 100 s−1, the crack growth velocity is small compared to the critical crack growth velocity and the effect can be ignored. The strengths of the granite obtained by micromechanical modelling agree with the experimental results. A constitutive relation of the granite is derived from the energy equilibrium equation and correlated with the experimental results.
Simplified procedures for estimating the fundamental period of a soil profile
abstract A study was made of simplified procedures for estimating the fundamental period, T , of a linear or equivalent linear model of a soil profile. Closed form solutions and approximate methods for computing the first period of an elastic shear-beam representation of the profile were examined. Closed form solutions are presented in chart form for the following cases: (a) shear-wave velocity increasing as a power of depth, (b) shear modulus increasing or decreasing linearly with depth, (c) two-layer profile, and (d) overconsolidated or uniform crust on layer with modulus increasing with depth. Seven approximate methods developed to estimate the period of a layered soil profile without a computer were also discussed and evaluated. For this evaluation, the periods of 76 representative soil profiles were estimated by each one of the approximate methods, and the results compared with the exact values. Methods 6 (Successive Use of Two-Layer Solution) and 7 (Simplified Version of the Rayleigh Procedure) gave errors less than 10 per cent for the period in all cases considered, and these methods are recommended for practical use. The approximate methods and the closed form solution charts may be used to estimate the characteristic site period, T s , included in the proposed (1976) modifications to the seismic provisions of the Unified Building Code.