Tapi Irrigation Development Corporation Tender

Item No.3 - Multichannel Analysis of Surface Waves for one profile on earthen dam. MASW for one Profile on earthen dam top - First introduced in GEOPHYSICS (1999), the multichannel analysis of surface waves (MASW) method is one of the seismic survey methods evaluating the elastic condition (stiffness) of the ground. MASW, first measures seismic surface waves generated from various types of seismic sources—such as sledge hammer analyses the propagation velocities of those surface waves, and then finally deduces shear-wave velocity (Vs) variations below the surveyed area that is most responsible for the analysed propagation velocity pattern of surface waves. Shear-wave velocity (Vs) is one of the elastic constants and closely related to Young’s modulus. Under most circumstances, Vs is a direct indicator of the ground strength. After a relatively simple procedure, final Vs information is provided in 1-D, 2-D, and 3-D formats. Seismic methods are suitable to study the strength characteristics of dyke and dams. Seismic measurements are sensitive to density changes and compactness of soils. Therefore, areas with inadequate compactness of dykes can be detected. A correlation with SPT/CPT (Standard/Cone Penetration Testing) is often done because these methods also depend on the mechanical properties of the soil. The example below shows the result of a MASW (Multichannel Analysis of Surface Waves) measurement along a dyke in comparison to two CPT readings. The MASW procedure measures the shear wave velocity of the dyke material which enables the direct access to the material shear strength. Field Data Acquisition Procedure: Field procedure for active MASW survey is explained here. The active survey is the most common type of MASW survey that can produce a 2-D Vs profile. The overall setup is illustrated in Figure hereunder. The maximum depth of investigation (Zmax) that can be achieved from the survey is usually in the 10-30 m range, but this can vary with site and type of active sources used. Surface waves are best generated over a ‘flat’ ground within at least one receiver-spread length (D).

Item No. 4 - Report and Data Interpretation based on the Detailed Investigation, Detailed Project Report shall be prepared as directed by the Engineer-in-Charge and as per CWC guide lines and submitted in 5 (Five) sets (all documents) and also in soft copy.