Zhao Yang Geotechnic Pte Ltd began her business in 1997 as a local setup specializing in ground improvement and geotechnical engineering works. Today, we are the leading ground improvement and geotechnical engineering contractor whom our clients can always trust for top quality and innovative ground engineering solutions.
This technique uses a combination of high pressure (50 to 200 bars) jet grouting and mechanical mixing blades with a high revolution of 40 to 90 RPM. Columns created with this technique are of an assured quality with uniform and consistent diameters (ranging from 0.6m to 2.6m) and WSM has a proven treatment depth of up to 53m in Singapore. With this technique, side-nozzles jetting can also be used near D-Wall/CBP Wall/SBP Wall/ Sheet Piles Wall for contact Ground Improvement Works.
Jet Grouting is a general term used to describe various construction techniques used for ground modification or ground improvement works. These techniques involve injecting ultra high-pressure fluids or binders into soils at high velocities. These binders break up the soil structure completely and mix the soil particles in-situ to create a homogeneous column mass, which in turn solidifies. High pressure double tube jet grouting uses a combination of air and grout to increase efficiency of the mixing process and column diameter.
This ground modification / ground improvement of the soil plays an important role in the fields of foundation stability, particularly in the treatment of load bearing soils under new and existing buildings, in-depth impermeabilization of water bearing soils, tunnel construction, and mitigation of movement of soils and groundwater.
The TAM Grouting method, which uses the Tube-A-Manchette pipe and double-packer, is carried out by combining controlled compensation grouting and permeation grouting. A TAM pipe is usually perforated at intervals of 30 to 50 cm and is used with an inner grouting pipe containing two packer elements. TAM pipes installed in the ground will allow grouting to be carried out individually and repeatedly. The method provides precise control and flexibility which are required during the process of controlling settlement of buildings, roads and tunnels.
A Manchette tube is a PVC or metal pipe in which rubber sleeves cover holes that are drilled in the pipe at specific intervals. The tubes are inserted into holes that have been bored into the "work area" (soil, rock, concrete, etc.) known as the "grout zone". Grout is pumped to a packer that has been slid into the tube. Seals on the packer force the grout thru the holes in the tube, past the flexible rubber sleeve, and into the grout zone to help stabilize and/or seal it.
Fissure Grouting is defined as the grout infilling of discontinuities, fissures, fractures or joints in mass rock with the intention of reducing permeability and increasing the competence of the mass rock. This technique is frequently employed for dam construction and tunnelling. Grout injection will be by cement grout or other materials depending on the size of fissures.
Rock Grouting is the injection of a slurry or grout into the subsurface profile. The grout fills cracks and voids and is used to strengthen the ground or to make it more water resistant. There are many kinds of soil grouting and rock grouting, which are specialized for different soil types and different project requirements. Grouting work can be simple or complex, highly laborious or highly mechanized. Often the most important decision is the decision as to which grouting technique will be successful at the lowest overall cost.
Producing a slurry wall using Cement Mixing in-situ with native soil by WSM technique provide a cost effective solution for the construction of cut-of walls for groundwater control, walls for excavation support (retaining wall) and reservoir dam seepage control.
Chemical grouts were developed in response to a need to develop strength and control water seepage in geologic units where the pore sizes in the rock or soil units were too small to allow the introduction of conventional Portland-cement suspensions. The goal in this work was to bond the particles of soil or rock and to fill in the pore spaces to reduce fluid flow. The technology has expanded with the addition of Sodium Silicate and additives that can penetrate 100% into the soil & rock fissure in-order to control the strength and setting characteristics of the injected liquid. The chemical grouting is useful for silts and sandy layer.
Pile Base Grouting techniques are widely used to rectify the soft toe problem of bored piles. When bored and case-in-place piles are installed in granular soils, the drilling operation may loosen the soil surrounding the shaft and beneath the base of the pile borehole. Such loosening below the base can cause excessive working load settlement when the majority of the load is carried by end bearing. Base grouting is a means of restoring the original in-situ density and reducing settlement.
Piles are base grouted by varying the controlling parameters such as grout volumes, pressures and injection rates.
Cavity Grouting is most commonly, though exclusively, used for backfilling limestone formation cavity, sink holes and abandoned sewer pipe workings to avoid the development of settlement or worse, sink holes, at the ground surface, attributable to the collapse of large underground voids.
The process involves drilling into the cavity then pumping grout to either fill the void in part or in full as the design demands.
The Geopier® Impact System is an efficient and eco-friendly intermediate foundation solution for the support of settlement-sensitive structures such as buildings, roads, embankment, liquefaction mitigation and fuel & water tank. This is a patented system using vertical ramming and densification process that creates a stiff element that provides unsurpassed strength, stiffness and superior levels of performance. The Geopier® system has a proven track record, having supported thousands of projects in the USA and Europe.
Vibro Concrete Columns (VCC) is commonly used in areas that require higher loads and are installed through very soft and compressible soils in order to transfer loads to more competent load-bearing strata. VCC are used in cases where the soils are so soft and unstable that installation of stone columns would be difficult, or where the stone columns would not have sufficient lateral confinement to adequately carry vertical loads.
Ground anchors consisting of PC strand or rods connected to waler beams and anchor brackets are often used for retaining wall tie back, stabilization of steep slopes or slopes consisting of softer soils, as well as the enhancement of embankment or foundation soil capacity, or to prevent excessive erosion and landslides. PC strand with U-turn loop for removal ground anchors is often used to ensure that the strand is 100% removed after completion of basement works.
Ground anchors are constructed by boring a hole through a retaining wall or a wall to absorb soil and water pressure. Cement grout is used to fill up the bored hole before insertion of the tendon. The bore hole’s irregular shape ensures the maximum transfer of tensile forces from the anchor to the soil. The grout and sheathing protects the anchor against corrosion. The fixed length and free length of the anchor design are determined according to the retaining wall and the tensile forces to be absorbed.
Secant Soil Mix Pile Wall provide an alternative solution to conventional shoring systems like D-Wall, CBP, Sheet Piling and Secant Bored Pile Wall used to build embedded retaining walls often utilized for basement construction. Variations of the method include installation of I-beam at alternate soil mix pile or soil mix pile without I-beam.
The secant soil mix pile wall method has been a proven eco-friendly Earth Retaining Structure System (ERSS) in many projects undertaken by Zhao Yang Geotechnic Pte Ltd in Singapore. Secant soil mix pile walls are utilized to transfer lateral, vertical or a combination of both loads through weak soil layers to a suitable bearing layer. They can be drilled in all types of configurations that can form an interlocking watertight cut off wall, or provide for a structural overlapping wall. Secant walls are mainly used for foundation load transfer and earth retaining systems. They are used in land-based structures, top-down tunnel, cofferdams and subway structures where the surface soil layers cannot provide the required load-bearing capacity.
Soil nails / Rock bolts, consisting of high tensile rebar or FRP rebar connected to RC beam with lock nut and bearing plate, are often used for retaining wall tie back and slope stabilization works.
Shotcrete refers to concrete produced by the projection of wet sand and cement mixture onto an area, by means of pressure applied through a continuously feeding pressure vessel. This type of construction allows the concrete to follow irregular shapes and makes possible the shaping of the material as it hardens. It is the preferred technique for the shaping of swimming pools, ponds or even caves and buildings.
When properly mixed and applied, Gunite is extremely strong, dense and highly resistant to weathering and many forms of chemical attack. It is heat resistant to a high degree and can be made more so by substituting refractory aggregates for part or all of the sand. Resistance to abrasion is extremely high. The bond to other Gunite, well cleaned masonry or other materials is equal to or greater than the shearing strength of the material to which it is applied.
Micropile is another type of pile that acts as a supporting structure to transfer the load from the building to the ground. As the name implies, micropiles are small diameter piles constructed during the drilling process and are often keyed into rock. Various diameters of micropile can be found in the market, ranging from 150mm to 500mm. Of late, technological advancement in machinery has made it possible for micropile of much greater diameters to be constructed.
The pile body consists of grout with a steel reinforcement cage installed in the center of the pile. The pile body’s irregular shape ensures maximum friction between the pile and the soil, as a result of which the transfer of tensile or compressive forces between the pile and the subsoil is at a maximum. Using compact and flexible machines means that work can be carried out in small spaces such as cellars and building basements.
Micropiles can penetrate in excess of 60 meters in depth, with design loads of as much as 180 tonnes.
The casing and auger go in with one pass, and with a hollow auger the concrete is injected as the auger is withdrawn. The steel reinforcement is dropped or vibrated in.
A Bored Pile is a reinforced concrete pile, which is used to support tall buildings producing heavy vertical loads. Cast in-situ bored pile is a cast in-situ concrete pile where the bored piles have to be cast on the construction site, while other concrete piles like spun pile and reinforced concrete square pile are pre-cast concrete piles. A bored pile is cast by using a boring machine which has specially designed drilling tools, buckets and grabs to auger and remove the soil / rock in the bore hole up to the designed depth. After completion of the bore hole, reinforcement is inserted into bored hole and followed up immediately by concreting.
Soil Investigation includes drilling boreholes and collecting soil samples at desired intervals for subsequent observation of ground profile and laboratory testing. The boreholes will be made by the rotary drilling machine. Undisturbed samples will be taken at stipulated intervals using suitable type of samplers for different type of soils with dimensions conforming to the standard sampling tubes specification.
In-situ Standard Penetration Tests (SPT) will be carried out to provide an indication of the density and/or consistency of the ground and to obtain disturbed samples for visual inspection and laboratory testing and classification.
Other in-situ tests carried out include Pressuremeter test, CPT, Vane Shear test and Permeability test to obtain esired soil parameters.
Wireline rock coring system enables intact rock samples to be retrieved productively for laboratory testing.
Our soil investigation rigs are proven capable of conducting Horizontal / Raker investigation and rock coring works.
A recharge well (injection well, inverted well, diffusion well, or disposal well) may be defined as a well that admits water from the surface to underground formations. Its flow is the reverse of a pumping well, but its construction should be the same. Well recharging is practical in many geologic environments where aquifers must be recharged, and where economy of surface space, such as in urban areas, is an important consideration.
In nature, ground-water systems are always changing to some degree. Ground-water flow patterns are continually adjusting to natural and human-induced changes in the surrounding hydrologic environment. Although areas contributing recharge also change to reflect changes in ground-water flow patterns, the nature of how they change and the time scale over which that change occurs can be complex and difficult to analyze.
