MXPA98008247A - Vehicle arresting bed systems - Google Patents

Abstract

Vehicle arresting beds, for installation at the ends of aircarft runways, are effective to safely decelerate aircraft entering the bed. The arresting bed is assembled of a large number of blocks of cellular concrete (70) having predetermined compressive gradient strength, so that aircraft landing gear is subjected to drag forces effective to slow a variety of types of aircraft, while providing deceleration within a safe range of values. An arresting bed typically includes an entry region (52) of a depth increasing from 9 to 24 inches formed of blocks having a first compressive gradient strength. A second region (54), which may be tapered into the first region and increase in depth to 30 inches, is formed of blocks having a greater compressive gradient strength. An aircraft thus experiences increasing drag forces while it travels through the bed, to provide an arresting capability suitable for a variety of aircraft. A protective hardcoat layer (62) of cellular concrete of strength greater than the blocks overlays the blocks to enable service personnel to walk on the bed without damage. Arresting bed systems may be provided in alternative configurations, such as a bed formed of an aggregate including pieces of cellular concrete with or without interspersed pieces of other compressible material and covered by a hardcoat layer.

Description

VEHICLE DETENTION BED SYSTEMS FIELD OF THE INVENTION This invention relates to systems for decreasing the speed of vehicle displacement and? more particularly "to detention bed systems" of cellular concrete »to safely decelerate an aircraft that takes off at the end of a runway.

BACKGROUND OF THE INVENTION Aircraft can and do go beyond the ends of the runways, raising the possibility of damage to passengers and destruction to the aircraft or severe damage to it. Such exceeded routes have occurred during unfortunate takeoffs or while landing, moving the aircraft at speeds of 14T km / hr. In order to minimize the risks of overpasses, the Federal Aviation Administration (FAA) generally requires a safety area of 305 lengths beyond the end of the runway. Although this area of safety is now an FAA standard, "many tracks across the United States were built before their adoption and are located in such a way that water" railroads or other obstacles prevent economic compliance with the requirement in case of travel exceeded of the Several materials have been assessed »including the existing ground surfaces beyond the track» in terms of their ability to decelerate the aircraft. Soil surfaces are very unpredictable in their ability to stop because their properties are unpredictable. For example, "very dry clay can be very hard and almost impenetrable" but wet clay can cause aircraft to get stuck fast »cause the landing gear to break down and provide potential damage to passengers in the crew as of greater damage to the aircraft. A 1988 report is aimed at an investigation by the Port Authority of New York and New Jersey on the feasibility of developing a plastic foam detention mechanism for a runway at the International Airport JFK. In the report, it is stated that the analyzes indicated that such a detention mechanism design is viable and could safely stop an aircraft of 45 > 360 kg that exceeds the runway at an exit speed of up to 148 kg / h and an aircraft of 361 »945 kg that exceeds an exit speed of up to 111.2 kg / hr. The report states that the effectiveness of an appropriate confinement of the plastic foam stopping mechanism was shown to be potentially "superior to a 305 m overrun paved area" particularly when braking is ineffective and reverse proportioning force is not available. " As is well known »Braking effectiveness may be limited in conditions of wet surfaces or ice covers. (Report UDR-TR-S8-07 »of the University of Dayton» January 1988). More recently »an aircraft detention system has been described in the US patent. No. 5 »193» 7S4 by Larrett et al. According to the description of that patent "an aircraft stopping area is formed by adhering to each other a naturality of thin layers stacked with rigid fire-resistant" friable "foam foam, adhering the lowermost foam layer to a surface of support. The stacked layers are designed so that the compressive strength of the combined layers of rigid plastic rubber is less than the force exerted by the landing gear of any aircraft of the type designed to stop when moving to the track stopping area. " that the foam is crushed when the aircraft makes contact with it. The preferred material is pheonic foam used with a combative adhesive such as latex adhesive. Testing of the phenol foam based detention system indicates that while such systems can function to make the aircraft stop »the use of the foam material has disadvantages. Fundamental among the disadvantages is the fact that the foam »depending on its properties» can typically exhibit a bounce property. In this way, "great testing of the phenol foam stopping beds was noted which provided a certain forward momentum to the wheels of the aircraft as it moved through the foamed material" as a result of the rebound of the foam material itself. . Foamed or cellular concrete as material for use in detention bed systems has been suggested and has been field tested in the prior art. Such testing has indicated that cellular concrete has good potential to be used in detention bed systems on the basis of the provision of many of the same advantages as phenolic foam while avoiding some of the disadvantages of foam. phenol ica. However, the requirements for crushing resistance and material uniformity controlled accurately throughout the detention bed are critical and, as far as is known, the production of cellular concrete of appropriate characteristics and uniformity was not previously achieved or described. The production of structural concrete for construction purposes is an old technique involving relatively simple procedural steps. The production of cellular concrete "although it generally involves simple ingredients" is complicated by the nature and effect of the aspects of aeration, "mixing and hydration," which must be carefully specified and exactly controlled if a uniform final product is to be provided. be neither too weak nor too strong "for the present purposes. Discontinuities - including areas of weaker or stronger cellular concrete - can actually cause damage to the vehicle that is decelerating if, for example, deceleration forces exceed the strength of the wheel support structure. Such lack of uniformity also results in the ability to accurately predict the effectiveness of deceleration and the total stopping distance. In a recent feasibility test using commercial class cellular concrete, an aircraft equipped for the recording of the test data rolled through a bed section and load data was acquired. Although precautions have been taken to try to provide uniformity of production, the samples taken and the aircraft load data from the test stopping bed showed significant variations between areas in which the crushing resistance was excessively high. and areas in which it was excessively low. Obviously »the potential benefit of a detention system is compromised» if the aircraft is placed at forces that could damage or damage the main landing gear. A 1995 report »prepared by the Administration Federal Aviation »entitled" Preliminary Soft Qround Arrestor Design for JFK International Airport "describes a proposed aircraft detention mechanism. This report discusses the potential use of either phenol foam or cellular concrete. As for phenolic foam, reference is made to the disadvantage of a "bounce" characteristic that results in the return of a certain energy following compression. As for cellular concrete, called "foamcrete", it is noted that "it is difficult to maintain a constant density (resistance parameter) of foamed concrete" in production. It is indicated that foamed concrete can be a good option for the construction of stop mechanisms »if it can be produced in large quantities with constant density and compressive strengths. The flat-plate test is polished and the uniform compressive strength values of 4.22 and 5.62 Kg / cm2 are described over a deformation range of 5 to 80% with objectives based on the level of information then available in the art. The support then indicates the lack of availability of both existing materials that have acceptable characteristics and the production methods of such material, and suggests on a somewhat hypothetical basis that possible characteristics and the testing of such materials could be made available. . In this way »although they have been considered a detention bed system and a certain actual subjection to the test of various materials has been explored for them» the practical production and application of a detention bed system which, within specified distances » will safely decelerate aircraft of known size and weight that move at a projected speed detached from a runway »has not been achieved. The particular material to be used, as well as the configuration and fabrication of a "detention bed" are all critical to the provision of an effective detention bed system. To provide an effective stopping bed for vehicles of a range of sizes »weights and velocities at the entrance to the bed» requires the use of bed designs »materials and manufacturing techniques capable of providing predictable forward strength and deceleration rates of the vehicles. Computer program models or other techniques may be used to develop the objectives of resistance to the advance or deceleration of the detention beds "based on the calculated forces and energy absorption for aircraft of a particular size and weight" in view of the corresponding specifications of landing gear resistors for such aircraft. However, such objectives remain only an abstract goal in the absence of efficient bed configurations. materials and manufacturing techniques to properties to turn the objectives of detention beds into reality in order to achieve the desired results. As a result. Prior information on potential materials for detention beds and deceleration targets has been inadequate to enable fabrication to make a practical stopping bed suitable for use for commercial passenger aircraft and other vehicles. The objects of the invention are, for example, to provide new and improved stopping bed systems for vehicles and that such systems have one or more of the following advantages and capabilities: pre-cast cellular concrete assembly that has been submitted for acceptance »-block or aggregate assembly that makes possible the progressive variation of both depth and compressive strength characteristics; - predetermined stopping characteristics, substantially independent of weather conditions; -construction resistant to weather conditions and long term »-cover hard coating to support pedestrian access; -capacity of the vehicles of collapse / fire or rescue to maneuver completely on a detention bed; - ease of exit for passengers of a vehicle that has entered a detention bed; and - ease of repair by replacement of block or aggregate immediately after use by a vehicle that has overturned.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, the stopping bed system for vehicles introduces an initial section including first and second side rows of cellular concrete blocks having a first dry density in the lower portion in a range of 192.23 to 352.41 g / dm3. The blocks of the second row have a height incrementally greater than the height of the blocks of the first row. Also »the blocks of the first and second rows have a first compressive gradient resistance to provide deceleration to the vehicles. The bed system has an additional section including the third and fourth side rows of the cellular concrete blocks having a second dry density greater than the first dry density. The blocks of the fourth row have an incrementally higher height than the block height of the third row and the blocks of the third and fourth row have a second compressive gradient resistance »to provide greater deceleration to the vehicles. A hard coating layer is placed on the blocks of the first, the second, the third and the fourth row. The hard coating layer comprises cellular concrete having a dry density greater than the first and second dry density and a thickness not exceeding 10% of the average height of the blocks. A vehicle stopping bed system may desirably have additional features, such as the following. The blocks are preferably formed of cellular concrete having a wet density in the range from 240.28 to 368.43 g / dm3 and soldered in molds of predetermined sizes. By way of example, all blocks are a preferred embodiment are of the same length and width "but some are of different predetermined heights" with a first section of blocks having a compressive gradient resistance of 60/80 and a second section of blocks that has a compressive gradient resistance of 80/100. The hard coating layer may be formed of solidified cellular concrete at the location having a greater strength to provide general protection of the detention bed and allow maintenance personnel to walk on the bed without damaging it. For a better understanding of the invention "together with other additional objects" reference is made to the accompanying drawings and the scope of the invention will be indicated in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A »IB and 1C are respectively a plan view, and longitudinal and cross-sectional views» and a vehicle stopping bed system using a block construction according to the invention. Figures 2A and 2B are respectively similar plan view and longitudinal portions of a vehicle stopping bed system using agglomerated manufacture according to the invention. Figure 3 shows the dimensions of a typical block of cellular concrete suitable for use in a detention bed system. Figures 4 »5 and 6 show alternative constructions of cellular concrete blocks. Figures 7 and 8 show the results of tests in terms of compressive strength with respect to the percentage of penetration of samples of cellular concrete from two different resistances.

DETAILED DESCRIPTION OF THE INVENTION The use of cellular concrete in detention bed applications requires that the material be generally uniform in its resistance to deformation since it is the predictability of the forces acting on the surface of the contact members of the vehicle being stopped. which allows the bed to be designed and designed in such a way as to ensure an acceptable efficiency. In order to obtain such uniformity "there must be careful selection and control of the ingredients used to prepare the concrete cellular »the conditions in which it is prepared and its solidification regime. The cellular concrete ingredients are generally a cement »preferably Portland cement» a foaming agent and water. Fine sand and other materials can also find application in some circumstances »but they are not used in the currently preferred modalities. Portland type III cement is the type of cement currently preferred for application to detention beds. For the present purposes, the term "cellular concrete" is used as a generic term that includes concrete with relatively small internal bubbles of a fluid, such as air »and that may include sand or other material» as well as formulations that include such sand or other material. The construction of the detention bed system can be carried out by producing the cellular concrete in a central production facility or on the bed site and pouring the concrete into molds of appropriate dimensions to achieve the desired geometry for the system. However, in the interest of uniformity of material characteristics and general quality control "it has been commonly considered preferable with the sections of the total bed using appropriately sized molds and then transporting the sections to the site to be installed to provide the required conf Total bed configuration. In the latter case, such units or sections »in the form of blocks of predetermined sizes, may be produced and maintained until the completion of the quality control test. The blocks can then be placed on the site and adhered to the safety area of the track using asphalt, cement slurry or other suitable adhesive material. depending on the construction materials of the security area itself. In this case, according to the invention a hard coating is applied to the outer surface of the assembled stop bed to provide a stronger surface that does not deform as easily as the main structure of the bed itself. This allows maintenance to be carried out without serious damage to the deformation of the main structure. A preferred hard coating consists of foamed concrete in which the wet densities are somewhat higher, for example in the range of about 352.4 to about 416.49 g / dca. A film or protective paint resistant to weather conditions can finally be applied to give the structure a desired visual appearance and which acts as protection against degradation by weather conditions. Preferred coatings include water-based slab materials.

DEFINITION OF "COMPRESSIVE SRADIENT RESISTANCE" OR "RQC" The term "compressive strength" (not RGC) normally implies the amount of force (conventional measure in Kg / cmz) which, when a normal vector is applied to the surface of a standardized sample »will cause the sample to fail. The more conventional test methods specify the test apparatuses, "procedures for all samples," test specimen requirements (including size, molding, and diffusion requirements). carca regimes and record keeping requirements. An example is "Regular method for compressive strength of lightweight insulating concrete" of ASTM C 495-86. Although such conventional test methods are useful when designing structures that are required to maintain structural integrity under predicted load conditions (i.e., they have at least a minimum resistance) the object of the bed arrest systems is to fail so specific predictable »thus providing controlled and predictable resistive force» as the vehicle forms cellular concrete (ie, a specific compressive strength). In this way »such a conventional test focuses on determining the resistance to the point of failure, not the resistance during compressive failure. More simply stated, the knowledge that the amount of force will shatter a specimen of cellular concrete material does not solve the critical question of how much resistance to advance or deceleration is experienced by the vehicle moving through a bed system. of detention. In contrast to a "one time" fracture resistance as in the prior art, for the present purposes the test should evaluate a continuous compressive failure mode, as a portion of a specimen is continuously compressed to approximately 2054 of its thickness original. The equipment and methods suitable for such continuous tests suitable for the intended purposes have not generally been available in advance. Due to the extensive amount of available variables of materials and methods of processing cellular concrete "and the size and cost of constructing detention beds to be tested, it is imperative that accurate test information is available to predict the amount of resistive force that will provide a particular variety of cellular concrete, elaborated and solidified in a certain way »when. it is used in a detention bed system.

By developing a new testing methodology to focus the resulting data on the measurement of the resistive force that occurs during the continuous compressive failure of a sample, instead of a simple "compressive strength" of a time, new methods and devices have been developed. test to be possible the reliable test and confirmation of the appropriate materials of cellular concrete and the processing variables. As a result, it has been determined that the compressive force required to grind cellular concrete at 2054 of its original thickness varies with the depth of penetration. This feature, which the present inventors refer to as "compressive gradient resistance" or "RSC", must be precisely specified in order to construct a stopping bed of cellular concrete vehicles having known deceleration characteristics to safely decelerate an aircraft. In this way, the penetration type test method in which the compressive strength of a cellular concrete sample is due does not apply a force that fractures a sample, but rather continuously provides data on the resistive forces, generated according to its moving a test probe head that has a specified compressive contact surface, through a volume of cellular concrete, is essential to obtain the data necessary to formulate and use cellular concrete in applications to detention beds. As measured thus, the RGC will vary over an interval with penetration depth »resulting in a gradient value (such as RGC of 60/80 with an average RGC of 4.92 kg / cm * over the penetration range) rather than a single singular fracture value as the previous tests. For the present purposes "the term" compressive gradient resistance "(or" RGC ") is used to refer to the compressive strength of a section of cellular concrete from a surface and which continues at an internal depth of penetration that can typically be 66% of the thickness of the section. As defined »RTC does not correspond to the compressive strength determined according to the regular ASTM test methods. Suitable methods and test apparatus for determining the RGC are disclosed in the application "Serial No. 08 / 796,968" filed concurrently with the present "having a claimant incorporated herein by reference.

Voltage bed of Figures 1A, IB and 1C With reference to Figure 1 (including collectively Figures 1A.B and 1C) »an embodiment of a vehicle stopping bed system according to the invention is illustrated. As shown in Figure 1A »the bed has a length and a width and also a thickness as shown in Figures IB and 1C. The bed is configured to decelerate an aircraft entering the bed from the left in Figure 1A. Basically »the system of Figure 1 is constructed of pre-cast blocks of cellular concrete having two different compressive gradient resistors and a variety of different thicknesses, with installation provided at the end of the runway of an airport. The layers 50 supported by the system should usually be relatively flat, smooth and uniform (subject to having an appropriate slope for water runoff requirements) and capable of supporting aircraft leaving the runway. The layers 50 must be in good condition and satisfactorily cleaned for the placement and adhesion of the tension bed system. To show the vertical details, the vertical dimensions, the vertical dimensions of Figures IB and 1C are enlarged in relation to the dimensions of Figure 1A (for example, the width of the bed in Figure 1A can typically be 45.72 »while the maximum thickness of the bed in Figures 1A and 1C can be typically in the 76.12 cm), also, certain dimensions, such as the size of the block »are distorted for clarity of the illustration (for example» instead of showing the thousands of blocks actually included in a typical voltage bed). A typical block suitable for use in the system of Figure 1 is illustrated in the figure. As shown, block 70 can be manufactured by placing the wet cellular concrete in standard molds 64 (typically 1.22) wide and 76 (typically 2.44 m) uniform in width. The thicknesses of blocks 72 can be varied to a range of 20.32 to 76.2 cm "for example, to provide blocks having varying heights in increments (typically from 1.91 cm height increments for a fine taper to 7.62 cm increments) to The provision of tapered bed configurations anterior to posterior capable of providing predetermined incremental increases in forward strength forces is possible. In the block mode shown in Figure 3, slots 78 and 80 of transverse lift are included. Slot 78 and 80, suitable for use with the type of lifting mechanism with biforcated bars, are formed by placing rectangular white lightweight plastic on the bottom of a mold when the block is cast. Other features and configurations of useful blocks in a detention bed constructed in accordance with the invention will be discussed with reference to figures 4, 5 and 6.

As shown »the vehicle stopping bed system of the figure has a cell concrete bed area that includes a first section 52, comprising a block assembly having a first RGC and a first dry density, and a second section 54, comprising an assembly of blocks having a second RGC and a second dry density. As shown in the side sectional view of figure IB, sections 52 and 54 partially overlap (in what might be considered section 52/54), with an obscured line indicating the union in which certain blocks of section 52 are located on the blocks of section 54 in a transition region. In a particular embodiment, the blocks of section 52/54 can actually be mixed blocks (ie, single blocks that include a portion 52 with a first RGC and a portion 54 with a second RGC). In other modes »separate blocks of different RGCs can be stacked for section 52/54. More particularly, the systems of the vehicle stopping bed of the type illustrated in Figure 1 include a first block side row (eg, row 52a) of cellular concrete having a first RGC and a first dry density in the range of 208.25 to 296.39 gr / cm3. Each of the blocks in the first row 52a has a first height and is made to be made vertically compressible at a compressed height (eg, compressible typically at approximately 20% of its initial thickness). These blocks can be manufactured to exhibit a RGC characteristic of 60/80, as shown in Figure 7 which will be discussed below. As shown in the figures the and Ib, the first section includes a second row 52b and a plurality of additional side rows illustrated as the rows 52c to 52n. formed of cellular concrete that has the same basic characteristics as the blocks in the row 52a, in some of which differ from row to row by a differential height index increases !. Also, as discussed with reference to the overlap section 52/54, certain rows of blocks, such as row 52n, overlap the blocks of row 54d on a base of mixed blocks or stacked blocks. In this embodiment, successive changes 1.91 cm thick were used in section 52 to provide tapered or tilt characteristics that result in gradually increasing vehicle stopping capabilities. The corresponding changes of 7.62 in thickness were used in section 54, in this particular design. Bedding systems of the illustrated type also include a third side row 54g of cellular concrete blocks having a second dry density that may be at a higher level in the same range as the first blocks of section 52. As shown in FIG. shown, the side row 54g is positioned parallel to the first side row 52a and behind it. The row 54g is followed instead by a side row 54h of incrementally greater height.

The section blocks 54 are made to be made vertically compressible subject to a second compressive gradient resistor, which will be generally specified to exceed the RGC of the blocks of section 52. These blocks may be manufactured so as to exhibit a characteristic of RGC 8O / 10O »as shown in figure 8 which will be discussed below» and a dry density in a range of 256.30 to 336.40 g / dm3. In the illustrated embodiment, the first row of block 54a of section 54 includes only a single course or layer of second RGC. The successive rows of section 54 include the increasing thickness of the second RGC material "until the blocks of section 54 reach the full height of stopping bed beyond section 52. The successive rows of section 54 increase after thickness in increments of 7.62 cm before reaching the maximum height in a subsequent level portion comprising rows of the same thickness that continue to the final back row 54n. Rows of increased height »such as row 54n» may be formed of two or three superimposed blocks of reduced thickness or rows of relatively thick single blocks »depending on manufacturing considerations» handling and transfer to the core. Figure 7 illustrates the RGC characteristics of a sample of cellular concrete representative of a block of section 52 of figure 1 determined by the tests. In Figure 7, the lower scale represents the percentage of penetration of the test area expressed in tenths of the thickness or height of the sample. The vertical scale represents the compressive strength of the test probe expressed in kg / cm3. The test data of main interest are typically within the penetration range of 10 to 60% of the sample thickness. Data beyond this range may be less reliable »effects of crushed material formation occurring beyond approximately 70% penetration As illustrated in Figure 7» the resistance the lack of cellular concrete exhibits a gradient with resistance to the compression that increases with the depth of penetration. For a particular design of a detention bed as illustrated in Figure 1, the line through points A and B in Figure 7 represents a generalized RGC of 60/80 »that is» an RGC characterized by a resistance of compression ranging from approximately 4.22 kg / cm * to approximately 5.63 kg / cmz over a penetration range of 10 to 66%. The average about this interval is then nominally equal to 4.92 kg / cm2 at the midpoint C. In figure 7, the line joining points A and B represents a typical generalized compressive strength gradient line for the section blocks 52 of figure 1 Figures D and E represent the quality control limits and line F represents the actual test data recorded for a specific test sample of cellular concrete. In this example, a test sample for which the test data is linked to a penetration range of 10 to 60 percent remains within lines D and E of the quality control limit. It represents a voltage block manufactured within These tolerances are acceptable. Fig. 8 is a similar illustration of RGC characteristics of a test sample of a block suitable for use in section 54 of Fig. 1 which has a RGC of 80/100 which is nominally equal to 6.33 kg / cmz, averaged over a selected penetration (for example, a penetration interval of 10 to 6654). For the present purposes "is defined" nominal "or" nomi to the entity "in reference to a value or a relation that is within approximately more or less 15% of a value or established relation. As shown, the system of FIG. 1 also includes an inclined entrance ramp 56, placed across the front side of the vehicle entrance of the first side row 52a. The ramp, which may be formed of a mixture of asphalt or other permanent type material, tapers a height adjacent to the blocks of the row 52a. which is typically greater than the compressed row of row blocks 52a. In a particular embodiment, a ramp height of approximately 7.62 cm adjacent to 20.32 cm blocks having an estimated minimum compressed height of 4.57 cm was used. The ramp 56 is thus effective to gradually bring the aircraft above the general runway level, so that the aircraft can enter the stopping bed on a relatively smooth basis, as the routes leave the ramp 56 and begin to compress the blocks of row 52a. Also included in the system of Figure 1 is a hard coating layer 62 »in the form of a relatively thin protective layer of cellular concrete material» which lies on top of the blocks of both section 52 and section 54 (represented by the uppermost limit line of the bed in Figure IB). In the figure the hardcoat layer is depicted as transparent in order to show the underlying details "although the hardcoat layer will typically not be transparent. In a preferred embodiment, the hard coating layer 62 comprises a relatively thin layer of cellular concrete having strength to support a pedestrian (eg, sufficient to support a maintenance person walking on the stopping bed) and may be cover of a similar paint or coating resistant to weather conditions. The layer 62 is applied on the detention bed after all the blocks of sections 52 and 54 are properly placed and adhered to the support surface 50. The hard coating layer 26 can typically be formed of cellular concrete with density dry from 352.41 to 416.49 g / cm3, with an average thickness of approximately 2.54 cm. In a stopping bed which may include blocks varying in thickness from 20.32 to 50.8 cm, the thickness of the hard coat layer 62 will typically not exceed 10% of the average thickness or height of the blocks and may be closer to the thickness of the blocks. 5%. Since the thin layer of hard coating has relatively little effect on deceleration of the aircraft, it is not necessary to typically subject the test samples to tests as described above. As illustrated, the detention bed system is also contaminated with a protection against debris 58 and entry ramps for service vehicles 60. The protection 58 can be formed from relatively light weight aluminum foil block to divert the particles thrown by the jet aircraft, etc., but sufficiently fragile to yield easily to the tires of an aircraft. OS ramps are provided and constructed to be possible for airport fire or rescue vehicles to climb over the detention bed in order to provide assistance to passengers on an aircraft that has come to a stop within the limits of the detention bed. . The ramp 60 may be constructed in a staggered manner, with elongated blocks of cellular concrete of appropriate strength or other suitable material. As shown, the ramp 60 is constructed of blocks of square cross-sectional dimensions that can be accommodated by a fire or rescue vehicle that moves over the bed. In a typical installation of the detention bed, appropriate to stop the advance of a variety of aircraft types »the blocks of section 52 can typically have thicknesses varying in increments of 1.91 cm from 22.86 cm to 60.96 cm» a dry density of approximately 304.38 g / dm3 in provide an RCG of 60/80 as described above. The blocks of section 54 may correspondingly have thicknesses that vary in increments of 6.72 cm to 6.96 cm to 76.2 cm "a dry density of approximately 304.36 cm and provide an RGC of 80/100. In the manufacture of the blocks, the blocks of section 52 can be formulated from cellular concrete having a wet density towards the lower portion of a range of approximately 224.26 to 368.43 g / dm3 »with the blocks of section 54 manufactured from cellular concrete having a wet density towards the upper portion of such range. The mixed blocks in section 52/54 would correspondingly consist partially of material with RCG of 60/80 and partially of material with RCG of 80/100. In total »sections 52 and 54 can have a joint length of 121.92 m» a width of 45.62 m and thicknesses front and rear end of 22.86 cm to 76.2 cm, respectively. It will be appreciated that for any particular application of the invention the effectiveness achieved will be dependent on the characteristics of the materials and the design of detention material as specified and manufactured in order to meet the identified effectiveness objectives specific to the product. . The parameters related to the materials to the systems with any specific application are beyond the scope of the present purposes and discuss the specific values only as general examples as possible parameter quantities. As described, the two main sections 52 and 54 can be constructed by the contiguous assembly of pre-molded blocks which are then cast with cement otherwise adhered to the supporting surface. Alternatively, other driving modes according to the invention may be employed. For example, with control of the appropriate procedure, a detention bed similar to the one illustrated can be poured and solidified in place on a unitary or sectioned base. Another mode of construction is illustrated in Figure 2 (comprising Figures 2A and 2B). Referring now to Figures 2A and 2B, there is shown a portion of a bed system for vehicle detection according to the invention that includes a bed 90 formed of an aggregate including cellular concrete floors. For the present purposes and harmony with the definitions of the dictionaries, "aggregate" is defined as a mass or volume of material formed of homogeneous or non-homogeneous units, pieces or fragments of equal or different sizes and of regular or irregular shape. According to the invention, an aggregate as the bed 90 is used may consist entirely of pieces of cellular concrete, which typically have dimensions less than a quarter of the average thickness of the bed, or may comprise pieces of cellular concrete with another material included in the mixture . Such other material may include pieces of phenolic foam or other compressible material, hollow glass spheres, hollow ceramic spheres or other trituarial articles of selected material and shape. As shown, the bed 90 has length, width and thickness and is configured to decelerate a vehicle, such as an aircraft entering the bed from the left. More particularly, as shown in Figure 2B, the aggregate of the bed 90 is unfolded to increase in thickness from left to right, so that some portions have different thickness than other portions. Furthermore, as indicated by 90A, there is indicated an inclined portion of aggregate that may have a compressibility higher than the portion of aggregate that is partially above the left of FIG. 2B. The bed may then include portions having different compressibility so that the resistance to washing or deceleration of the vehicle increases as a vehicle advances through the bed. The stop bed system of Figures 2A and 2B includes the edge members 92 and 94 along the perimeter of the bed 90 to restrict the aggregate from extending beyond the desired length and width of the bed., as illustrated »the same edge ones are cellular concrete blocks similar to those described above and each having a suitable RGC. In Figure 2A, each edge member 92 and 94 includes a row of blocks and the whole bed system would have an adequate total length "with an additional row of blocks through the right-hand end of the bed. The detention bed system, as illustrated, also includes a stabilizer layer, represented by line 96 in Figure 2B, which is located above bed 90 to limit aggregate movement within the bed. Stabilizing layer 96 may usually be a relatively thin hard coating layer of cellular concrete as described above. In Figure 2 the stabilizing layer is shown transparent in order to show the underlying details. Figures 4, 5 and 6 illustrate particular embodiments of cellular concrete blocks usable in the systems of the detention bed according to the invention. The block of Figure 4 is a mixed block that includes a 100% upper portion of cellular concrete having a desired RCG and a thinner lower layer 102 of stronger cellular concrete or other material to provide added strength, particularly during transportation and installation. of the blocks. Figure 5 shows a block of cellular concrete 104 that includes within its lower portion reinforcing members, illustrated as a fiber grill, metal or other suitable material. Figure 6 illustrates a block 10B of cellular concrete containing within it crushable pieces or shapes of another material. As represented in somewhat idealized form, such material may comprise one or more of: regular or irregular pieces of compressible material; glass or ceramic spheres. Hollow articles of selected material and form; or other suitable parts. Such items or materials will typically be placed near the bottom or distributed throughout the block and have a minor effect in slowing down a vehicle. or will be taken into account in the determination of the RGC. or both The nature of a cellular concrete detention bed system is such that its construction will be inherently relatively time-consuming and costly. Therefore, it is important that the method and training used to design the system be sufficiently reliable to correlate it with effectiveness, and predict it, under actual conditions of use. The bed of a computer modeling program, data obtained by the appropriate test methodology, or both, can provide the necessary correlation between prediction and field results. In general, to be effective a computer modeling program must be willing to accept data on the weight, the center of gravity, the moment of inertia, the structure of the three landing and the effort capacity and the projected speeds of the aircraft at the entrance to the bed. The details of a geometric configuration of the selected bed and of material strength in relation to the crushing of the stopping bed as the vehicle moves through are also typically input to the program. The program would be configured to use this information in order to provide the output data relating to deceleration with respect to the distance and resultant loads on the nose and the main landing gear at different speeds. The necessary information on the strength of the materials for the program can be provided in one of two ways. First, the actual test information can be used using the test methodology for cellular concrete samples in the program. In this way, the program accepts the characteristics of the material of a selected formulation of cellular concrete as fixed information and determines the results based on that information. Alternatively, it can be assumed that the cellular concrete to be used will exhibit some characteristic drag force. Afterwards, the designers of the detention bed can use the test methodology described above to identify the formulas »processing techniques and solidification regimes of cellular concrete that will result in materials that match the design requirements. As an alternative to a broad computer modeling program, the design of the detention bed can be based more closely on preform tests. The bed sections can be constructed to test the use of cellular concrete from one or more compressive failure resistances. Aircraft, equipped wheel structures and other compressive structures can then be carried to the sample bed sections and the effectiveness of the resulting bed can then be determined and used in the design of a complete stopping bed. Many other alternatives and variations will be apparent to those skilled in the art having an understanding of the invention. For example, the beds or sections thereof can be of uniform or variable thickness, can have gradual or stepped thickness variation, can be of uniform or multiple RGC, can have unitary or stacked blocks or aggregates and can be of width and length total selections, as appropriate for applications and subparticles for aircraft or other private vehicles. Although the commonly preferred embodiments of the invention have been described, those skilled in the art will recognize that there may be other and further modifications without departing from the invention and it is intended to claim all modifications that come within the scope of the invention.

Claims (32)

NOVELTY OF THE INVENTION CLAIMS

1. - A vehicle stopping bed system »comprising: a bed of cellular concrete having length» width and thickness and configured to decelerate a vehicle entering said bed; a hard coating layer that is on said bed, said hard cellular concrete coating layer having a thickness not exceeding 10% of the average thickness of said bed and strength to support a pedestrian.

2. A vehicle stopping bed system according to claim 1, further characterized in that said bed is formed of cellular concrete having an understandability that is different at different points on the length of said bed.

3. A bed system for stopping vehicles according to claim 1 or 2 »further characterized in that the bed comprises side rows of cellular concrete blocks.

4. A vehicle stopping bed system according to claim 3 »further characterized in that said bed is assembled from previously molded blocks of common length and common width and includes blocks of different thickness.

5. A bed system for stopping vehicles according to the re-indication 1 »further characterized in that said bed comprises an aggregate that includes pieces of cellular concrete and said bed system further includes edge members arranged to restrain said aggregate to further extend beyond said length and said width.

6. A vehicle stopping bed system according to claim 5, further characterized in that said aggregate consists of parts that have dimensions that do not exceed 10% of the average thickness of said bed and said pieces of cellular concrete are characterized by one of: irregular size and shape; common size and shape.

7. A vehicle stopping bed system according to claim 5 or 6 »further characterized in that said edge members are formed of cellular concrete blocks placed along the perimeter of said bed.

8. A vehicle stopping bed system according to claim 5, 6 or 7, further characterized in that said bed includes pieces of cellular concrete having a compressibility that is different at different points on the length of said bed.

9. A vehicle stopping bed system, comprising: a bed of cellular concrete having length »width and thickness and including side rows of cellular concrete blocks» each block having a compressive gradient resistance predetermined over a depth of penetration to provide gradual deceleration of a vehicle.

10. A vehicle stopping bed system according to claim 9 »further characterized in that said bed system also comprises a hard coating layer which is on said bed» said layer of hard concrete cellular covering having a thickness that does not exceed 10% of the average thickness of said bed and resistance to support a pedestrian.

11. - A vehicle stopping bed system according to claim 9 or 10 »further characterized in that said bed includes a first side row of blocks having a dry density the inally equal to 272.32 g / dm3 and a second row lateral of blocks that has a dry density nominally equal to 304.36 g / dm3.

12. A vehicle stopping bed system according to claim 11 »further characterized in that the blocks of said second side row have a thickness greater than the blocks of said first side row.

13. A vehicle stopping bed system according to claim 11 or 12 »further characterized in that the blocks of said first side row have a resistance of compressive gradient of 60/80 nominally equal to 4.92 kg / cm2 »when averaged over a penetration depth of said blocks.

14. A bed system for stopping vehicles according to the rei indication 9 »IO» 11 or 12 »further characterized in that said bed includes blocks having a compressive gradient resistance of 60/80 nominal equal to 4.92 kg / cmz »when averaging over a penetration surface of said blocks.

15. A bed system for stopping vehicles according to the re-indication 9 »10» 12 »13 or 14» further characterized in that said bed includes blocks having a dry density of a range of 192.23 to 353.41 g / dm3.

16. A vehicle stopping bed system according to claim 9 »10» 11 »12, 13, 14 or 15 »further characterized in that said bed includes shaped blocks of cellular concrete having a wet density in a range of 224.26 to 368.43 g / dm3» solidified in molds of predetermined sizes. 17.- A vehicle stopping bed system in accordance with claim 9, IO »11» 12 »13. 14. 15 or 16 »further characterized in that said bed includes cellular concrete blocks which are embedded in the same compressible pieces of a different cellular concrete material. 18. A bed system for stopping vehicles according to the rei indication 9"10" 11, 12, 13, 14, 15, 16 or 17, further characterized in that said bed includes cellular concrete blocks that include a lower layer of material with higher resistance. 19. A vehicle bed stop system according to claim 9 »10, 11, 12» 13 »14» 15 »16 or 17, further characterized in that said bed includes blocks of cellular concrete having reinforcement members embedded in them. 20. A vehicle stopping bed system comprising: a bed formed of an aggregate that includes pieces of cellular concrete, said bed having length, width and thickness and configured to decelerate a vehicle entering said bed; edge members positioned along the perimeter of said bed to restrain said aggregate to extend beyond said length and said width; and said stabilizing layer that is on said bed to limit the movement of said gift within said bed. 21. A vehicle stopping bed system according to claim 20, further characterized in that said edge members are formed of cellular concrete blocks, placed along said perimeter. 22. A vehicle stopping bed system according to claim 20 or 21, further characterized in that said stabilizing layer is a layer of cellular concrete having a thickness not exceeding 10% of the average thickness of said bed and resistance to support a pedestrian. 23. A vehicle stopping bed system according to claim 20, 21 or 22, further characterized in that said aggregate further includes crushable pieces of a different cellular concrete material. 24. A vehicle bed system according to claim 20, 21, 22 or 23 »further characterized in that said aggregate has a different thickness in different portions of said bed. 25. A vehicle stopping bed system according to claim 20, 21 »22» 23 or 24 »further characterized in that said aggregate has different compressibility in different portions of said bed. 26.- A vehicle stopping bed system »comprising: a first side row of cellular concrete blocks having a first dry density in the range of 192.23 to 352.41 g / dm3» the blocks of said first row having a first height; a second side row of cellular concrete blocks having a dry density nominally equal to the first dry density, the blocks of said second row having an incrementally greater height than said first height; a hard coating layer which is on the blocks of said first and said second row, said hard concrete coating layer having a dry density greater than said first dry density and a thickness not exceeding 10% of the height average of said blocks. 27. A vehicle stopping bed system according to claim 26. further characterized in that the blocks of said first and said second row have a compressive gradient resistance of 60 / SO nominally equal to 4.92 kg / cm2, when average over a penetration depth of said blocks. 28. A vehicle stopping bed system, comprising: first and second side rows of cellular concrete blocks having a first dry density in the range of 192.23 to 352.41- g / dm3 »having the blocks of said second row a height substantially greater than the height of the blocks of said first row and the blocks of said first and said second row having a first compressive gradient resistance to provide deceleration to the vehicles; third and fourth side rows of cellular concrete blocks having a second dry density greater than said first dry density »the blocks of said fourth row having a height that is greater than the height of the blocks of said third row and having the blocks from said third and said fourth row a second compressive gradient resistance »greater than said first compressive gradient resistance, to provide greater deceleration to the vehicles; and a hard coating layer lying on the blocks of said first said second said said third and said fourth row comprising said cellular concrete hard coating layer having a dry density greater than said first and said second dry density and a thickness that does not exceed 10% of the average height of said blocks. 29. A vehicle stopping bed system according to claim 28 »further characterized in that the blocks of said first and said second row have a comprehensive gradient resistance of 60/80 nominally equal to 4.92 kg / cm2 and the blocks of said third and said fourth row have a compressive gradient resistance of 80/100 nominally equal to 6.33 kg / cm3 »when averaged over a penetration depth into said respective blocks. 30. A vehicle stopping bed system according to claim 2B or 29 »which additionally includes at least one side row of mixed blocks partially formed of cellular concrete having said compressive gradient resistance of 60/80 and partially of cellular concrete having said compressive gradient resistance of 80/100. 31.- A vehicle stopping bed system according to claim 28 »29 or 30» further characterized in that said blocks are formed of cellular concrete having a wet density in the range of 224.26 to 368.43 g / dm3, soldered in predetermined forms and patterns. 32.- A vehicle stopping bed system according to claim 28 »29» 30 or 31 »further characterized in that said hard coating layer is formed of cellular concrete having a wet density in the range of 352.41 to 416.49 g / dm3, which solidifies in the place that is on said blocks. SUMMARY OF THE INVENTION Vehicle stowage beds, for installation at the ends of aircraft tracks, are effective in safely decelerating aircraft entering the bed; the detention bed is assembled from a large number of cellular concrete blocks having predetermined compressive gradient resistance, so that the landing gear of the aircraft is subjected to effective drag forces to slow down a variety of aircraft types, while at the same time providing deceleration safely within a range of values; A stopping bed typically includes an inlet region of a depth that increases from 22.86 to 60.96 cm "formed of blocks having a first compressive gradient resistance" a second region "which may be tapered towards the first region and increase in depth to 30.48 cm, is formed of blocks that have a greater resistance of compressive gradient; an aircraft thus experiences increasing forces of drag as it advances through the bed, to provide adequate stopping capability for a variety of aircraft; a protective layer of hard concrete coating, with greater strength than that of the blocks, is on the blocks to enable service personnel to walk on the bed without damaging it; the systems of the stopping bed may be provided in alternative configurations, such as the bed formed of an aggregate including pieces of cellular concrete with interspersed pieces, or without them, of another compressible material and covered by a hard coating layer. * »GC / ram * asg * xam * amm P98-1086F