Cross Holes

Industrial experience shows that components with filigree and complex part geometries, unfavorable mass distribution, undercuts, and cross-holes can be produced in one stage of operation in a near-net-shape manner by means of thixoprocesses. 

In order to eliminate boundary effect, the No. 1 cross-hole of the floor gateway of 1152 working... 

Low-strain tests that require borings include down-hole test, up-hole test, cross hole test and suspension logger test. Among these methods, cross-hole test is widely used to measure the... 

Maximum shear modulus of soil (G ) is the fundamental property of the soil in geotechnical earthquake engineering application. The most reliable methods to determine the maximum shear modulus of soil are those conducted in the field. This is because the laboratory soil testing of undisturbed soil samples is often subjected to errors due to sample disturbance. Evenifthe disturbance is minor in advanced technique of sampling, time and expense may be substantial. Hence in the present study shear wave velocity obtained from the cross hole test is utilized to compute the maximinn shear modulus of the soil using the formula discussed earlier. 

Shear wave velocity in Layer / in (m/s) The average shear wave velocity for the upper 30m computed using the cross-hole test data. The average shear wave velocity in the top 30m for most of the locations varies between 400m/s to 600m/s and is classified as C class site as per... 

Figure 3. (a)Typical wave trace obtained from the cross hole test (b)Typical variation of P-wave and S-wave velocity in the study area... 

The overall soil profile of 60 m thickness is divided into layers of 1.5 m thick is considered. Each layer is characterized by the unit weight of soil obtained from SPT data and shear wave velocity obtained from the seismic cross hole test data. A typical input soil data used in SHAKE analysis is presented in Figure 9. The water table is taken to be at a depth of 30 m below the ground level. 

Based on the extensive shear wave velocity measurement carried out at the site by cross hole test, most locations in the site are classified as C class except a few locations as B class as per NEHRP classification. 

ASTM standard D 4428-M (2007). Standard test methods for seismic cross hole testing. ASTM International, West Conshohocken, PA, 2003, DOI 10.1520/D4428 D4428M-07. 

Type Diameter Active Free cross Hole size Cell length... 

In some cases, there are dimensional variations greater than those which can be accommodated by oversize holes. A solution to that problem is the use of criss-cross slots (Fig. 8.266) in the moldments in conjunction with a nut, bolt, and washers. It should be noted that criss-cross holes are more expensive to tool or machine than roimd holes. 

Figure 8.26 Oversize holes (a) oversize hole with washer and (6) criss-cross holes. (Source Jordan I. Rotheiser, Joining of Plastics Handbook for Designers and Engineers, Hanser Publishers, Munich-Hanser Gardner Publications, Inc., Cincinnati, 19. )...

For hazard category 1 and 2 research reactors, dynamic characteristics of the soil profile may be determined by means of cross holes or geophysical methods up to the base rock or to a depth of at least 1.5 times the maximum foundation depth. The dynamic characteristics of the soil material for each layer may include ... 

If there is no access to a seismic CPT, shear wave velocity can also be measured by lowering geophones down a PVC cased borehole and measuring shear wave arrival times at regular depth intervals down the hole. The shear wave source can either be at the ground surface (vertical shear wave velocity profiling) or in an adjacent borehole (cross hole shear wave velocity measurement). 

Seed et al. (1983) adapted Ohaski and Iwasaki s (1973) relationship based on data collected following liquefaction events. Sykora and Stokoe (1983) measured using the cross-hole method and used 229 data pairs to develop their correlation. Fumal and Tinsley (1985) based their... 

Hegazy and Mayne (1995) used the general form of equations developed by Mayne and Rix (1993) and replaced initial void ratio, eo, and cr and with fs. This correlation was based on Vs from crosshole, down-hole, SASW, and the seismic cone penetration tests (SCPT) from 30 sites in the United States, Canada, Norway, and Italy. Mayne and Rix (1995) complied data from cross-hole, down-hole, SASW, and SCPTs conducted at 31 clay sites in Europe and North America and proposed a Vs-qc relationship. 

Determining d5mamic soil properties directly from measured shear wave velocities such as by the SCPT is obviously more accurate than estimates of Fj based on correlations with CPT resistances. Additionally, research has shown excellent agreement between Fj measured using the SCPT with other methods of measuring Fj, such as down-hole tests, cross-hole tests, SASW, and laboratory measurements (Robertson et al. 1992 Lunne et al. 1997 Schneider et al. 1999, 2001 Mayne 2000 Saftner et al. 2011 etc.). 

Bellotti et al. (1986) used cross-hole testing in Po River sand to determine the correlation presented in Eq. 22. 

Puente Hills landfill California, USA Cross-hole Earth Technology 1988... 

Shear wave velocities can be measured in situ by several seismic tests, including cross-hole and down-hole, seismic cone penetrometer, suspension logger, SASW (spectral analysis of surface waves), and MASW (multichannel analysis of surface waves). A review of these test methods is given in Woods (1994) and Kramer (1996). Their accuracy can be sensitive to procedural details, soil conditions, and interpretation techniques. Fig. 5 shows the layouts and principles of three established geophysical tests the continuous surface wave (CSW) method, the down-hole... 

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