Followed the proposed ECT procedure that was the injection of 0.75 M CaCl2 solution for 72 h, then 1.5 M KOH solution for 48 h, then sodium silicate solution for 72 h and then deionized water for 168 h, the clay strength can be improved from anode to cathode entirely. To further improve the clay strength, curing the sample for different periods and applying electric field over the sample were studied. The cone resistance, water content, pH value, Ca2+ concentration and the XRD pattern were tested or analyzed in each test. Results show that injection of deionized water was a key phase to produce a full improvement of the treated clay, which cannot be replaced by the application of an electric field only and without injecting water. Curing the treated clay after injecting deionized water can yield a higher clay strength in the cathode area significantly due to pozzolanic reaction but produce a lower clay strength in the anode area because the formed NaOH decomposed the gel structure of the sodium silicate solution. To obtain a better strength after injection of deionized water for 168 h, the treated clay had to be cured for about 28 days, along with a dry anode compartment.
The implementation of buckling‐restrained braces (BRBs) for new reinforced concrete frame (RCF) constructions is limited. This study investigates the seismic forces and stability in the BRBs and gussets of a 2‐story full‐scale RCF specimen by using Abaqus models and a newly proposed stability evaluation method. The hybrid and cyclic loading test results are accurately predicted by the Abaqus analyses. Existing methods for computing the gusset interface forces for steel buildings from both the brace and the frame actions are compared with the Abaqus results. The applicability of these methods for the BRB‐RCF design is critically evaluated. It is confirmed that the Parallel‐2 method is suitable for estimating the BRB force demand imposed on the corner gusset and the generalized uniform force method is good for the corner gusset at the base. In addition, existing stability evaluation methods for BRBs and gussets are applied to investigate the out‐of‐plane (OOP) buckling of the first‐story BRB observed at the end of tests. The proposed stability model incorporates the BRB restrainer's flexural effects and 4 rotational springs in assessing the BRB's buckling. This model confirms that the BRB and the gusset's OOP buckling limit states could be coupled and must be evaluated together. By incorporating the flexural effects of the steel casing and the infilled grout, the proposed model satisfactorily predicts the OOP buckling of the first‐story BRB and gussets. These research results can be used for the implementation of BRBs in new RC frame constructions. 相似文献
Release of an estimated 150,000 gallons (568,000 L).of 1.2–dichloroethane (EDC) from a buried pipeline into a ditch and surrounding soil resulted in shallow subsurface contamination of a Gulf Coast site. Short-term remediation included removal of EDC DNAPI. (dense nonaqueous phase liquid) by dredging and vacuuming the ditch, and by dredging the river where the ditch discharged. EDC saturation in shallow impacted sediments located beneath the ditch was at or below residual saturation and these sediments were therefore left in place. The ditch was lined, backfilled, and capped. Long-term remediation includes EDC DNAPL recovery and hydraulic containment from the shallow zone with long-term monitoring of the shallow, intermediate, and deep (200 foot) aquifers. Ground water, DNAPL., and dissolved phase models were used to guide field investigations and the selection of an effective remedial action strategy. The DNAPL. modeling was conducted for a two-dimensional vertical cross section of the site, and included the three aquifers separated by two aquitards with microfractures. These aquitards were modeled using a dual porosity approach. Matrix and fracture properties of the aquitards used for DNAPL modeling were determined from small-scale laboratory properties. These properties were consistent with effective hydraulic conductivity determined from ground water flow modeling. A sensitivity analysis demonstrated that the vertical migration of EDC was attenuated by dissolution of EDC into the matrix of the upper aquitard. When the organic/water entry pressure of the aquitard matrix, or the solubility of EDC were decreased to unrealislically low values. EDC DNAPL. accumulated in the aquifer below the upper aquitard. EDC DNALM, did not reach the regional (deepest) aquifer in any of the cases modeled. The limited extent of vertical EDC migration predicted is supported by ground water monitoring conducted over the four years since the spill. 相似文献